WO1991019730A1 - Rna hydrolysis/cleavage - Google Patents

Abstract

The selected sequence-directed hydrolysis of RNA under physiologically relevant conditions is described using conjugates comprising metal complexes covalently linked to oligodeoxynucleotides as hydrolysis agents. The oligodeoxynucleotide portions of the agents are selected to provide molecular recognition via the Watson Crick base pairing to the target RNA sequence to be hydrolyzed. A method is described for determining the RNA hydrolysis effectiveness of metals and ligands used to form the metal complexes useful in this invention. Also the selected sequence-directed cleavage of RNA is described using conjugates comprising two or more imidazole groups covalently linked to oligodeoxynucleotides as cleavage agents and combinations of conjugates comprising one or more imidazole groups covalently linked to two or more oligodeoxynucleotides. The oligodeoxynucleotide portions of the agents are selected to provide molecular recognition via the Watson Crick base pairing to the target RNA sequence to be cleaved.

Description

RNA HYDROLYSIS/CLEAVAGE

FIELD OF INVENTION

This invention relates to sequence-directed RNA hydrolysis under physiologically relevant conditions and particularly to metal complexes covalently linked to oligodeoxynucleotides as sequence-directed RNA

hydrolysis agents and to RNA cleavage generally and particularly to two or more imidazoles covalently linked to oligodeoxynucleotides as sequence-directed RNA cleavage agents.

BACKGROUND OF THE INVENTION

Recently hydrolysis of phosphate esters has received extensive investigation as reported in the art due to the relevance of this chemistry to biological systems, and specifically transition metal complexes have been examined as phosphate ester hydrolysis

catalysts in order to model the reactions catalyzed by the ATPase and phosphatase classes of enzymes and also particularly as it relates to the manipulation of the phosphodiester backbone of ribonucleic acids (RNA).

Such reported studies have generally employed activated p-nitrophenyl phosphate esters or phosphate anhydrides (ATP) as substrates (R. D. Cornelius, Inorg. Chem . 1980, 19, 1286-1290; P. R. Norman et al, J. Am. Chem. Soc. 1982, 104, 2356-2361 and F. Tafesse et al, Inorg. Chem . 1985, 24, 2593-2594). It has been reported that

t tramine complexes of Co(III) are capable of promoting the hydrolysis of adenosine 3',5'-monophosphate (cAMP) (J. Chin et al, Can . J. Chem . 1987, 65, 1882-1884) and adenosine monophosphate (AMP) (J. Chin et al, J. Am. Chem. Soc. 1989, 111, 4103-4105). Also, it is known that many divalent cations are capable of catalyzing the hydrolysis of RNA (J. J. Butzow et al, Biochemistry 1971, 10, 2016-2027 and J. J. Butzow et al, Nature 1975, 254, 358-359). Additionally, zinc ion in the presence of imidazole buffers has been sliown to catalyze the hydrolysis of the RNA dimer 3',5'-UpU at 80ºC. (R.

Breslow et al, Proc. Natl . Acad. Sci . 1989, 86, 1746- 1750). The ribonuclease class of enzymes is known to hydrolyze RNA in vivo and in vitro (Blackburn et. al. The Enzymes; Academic Press: New York, 1982; Vol 15, Chapter 12, pp 317-433.), and the active site of many ribonucleases contains histidine residues believed to be involved in catalysis (Richards et al. Ibid., 1971, Vol. 4, Chapter 24, pp 647-806). In order to model the reactions catalyzed by the ribonucleases, investigations into phosphate ester hydrolysis have been carried out using imidazole and imidazole derivatives as models for histidine. Such reported studies have generally

employed activated p-nitrophenyl phosphate esters as the hydrolysis substrate, instead of RNA itself (Anslyn et al. J. Am. Chem. Soc. 1989, 111, 5972-5973, and Anslyn et al. Ibid. 8931-8932.). These activated esters are more easily studied than the true biological substrates for two reasons: they are more easily hydrolyzed, and since the product p-nitrophenolate anion has a strong characteristic color, the reaction may be followed by simple spectrochemical techniques. While these

analogues are convenient models for biological substrates, they are not accurate models (Menger, F. M. and Ladika, M., J. Am. Chem . Soc. 1987, 109, 3145.)

C. A. Stein et al, Cancer Research May, 1988, 48, 2659-2668 gives a detailed review on the application of antisense oligodeoxynucleotides as modulators of gene expression and concludes by proposing a more subtle and effective approach would be to attach a chemical group to the oligomer that can result in localized catalytic hydrolysis of RNA. This technique would be more specific than the use of a radical-producing group such as iron EDTA. Stein et al theorizes that a suitable RNA hydrolysis group would be an imidazole group, which is known to be involved in phosphodiester hydrolysis in the active site of ribonuclease enzymes.

The hydrolysis of RNA by imidazole buffers has been reported in the art (Breslow et. al. J. Am. Chem. Soc. 1986, 108, 2655-2659) and the mechanism of this reaction has been studied (Anslyn et. al. J. Am . Chem . Soc. 1989, 111, 4473-4482). Based on these studies, a bifunctional general acid-general base mechanism was proposed for the hydrolysis of RNA by imidazole.

University Patents, Inc. in PCT International Patent Application published under number WO 88/04300 on June 16, 1988 discloses RNA enzymes or ribozymes, acting as endoribonucleases, as catalyzing the cleavage of RNA molecules with a sequence specificity of cleavage greater than that of known ribonucleases and approaching that of the DNA restriction endonucleases, thus serving as RNA sequence-specific endoribonucleases. Ribozymes are entirely or partly comprised of RNA itself, and therefore are chemically and enzymatically highly unstable relative to Applicants' DNA-based compounds. Such instability detracts from the practical

applicability of RNA hydrolysis agents. Also ribozymes presently are available only at a high cost due to limitations of very low production volumes through molecular biology techniques.

C. B. Chen et al, J. Am. Chem. Soc. 1988, 110, 6570-6572 describes that 1,10-phenanthroline-copper(II) is effective for targeted cleavage of both RNA and DNA and thus is useful for sequence-specific cleavage of RNA. This teaching is directed to oxidative cleavage of RNA by metal complexes linked to DNA at a temperature of 65*C as opposed to the hydrolytic cleavage of RNA under physiologically relevant conditions required by

Applicants' invention. The ancillary reagents, in the quantities required to drive the Chen et al oxidative degradation of RNA, are not compatible with living cells; furthermore, the 1,10-phenanthrolinecopper-oligodeoxynucleotide conjugate employed is itself degraded oxidativelj under the conditions of oxidative RNA cleavage (the rεte of oxidative cleavage by the

1,10-phenanthrolinecopper system is similar for both RNA and DNA) . P. G. Schultz and coworkers in a series of articles (D. R. Corey et al, J. Am . Chem. Soc . 1988, 110, 1614-1615; R. Zuckerman et al, J. Am . Chem . Soc. 1988, 110, 6592-6594 and R. Zuckerman et al, Proc. Natl . Acad. Sci . USA 1989, 86, 1766-1770) have described the preparation of site-selective DNA and RNA hydrolysis agents comprised of an enzyme (staphylococcal nuclease, ribonuclease S, or mutants of these parent enzymes) covalently linked to oligonucleotides. In one report (D. R. Corey et al, Biochemistry 1989, 28, 8277-8286), the location of the linker arm and its length were varied, which resulted in changes in catalytic

efficiency and site of cleavage. These nucleic acid hydrolysis agents differ from our inventions in several important aspects: the nucleic acid cleavage behavior is provided by an enzyme, not the synthetic, small molecule hydrolysis agent (or enzyme mimic) that we have disclosed; enzymes are subject to proteolytic

degradation by other enzymes; staphylococcal nuclease is dependant on added calcium for its activity;

ribonuclease S is a noncovalent complex comprised of the S-protein and S-peptide derived from ribonuclease A, and this complex is subject to dissociation, which results in loss of cleavage efficiency and specificity;

oligonucleotide-staphylococcal nuclease conjugates were found to cleave DNA as well as RNA, thus lacking the specificity of our agents for RNA hydrolysis alone; this high activity limits the specificity of the enzyme-based systems developed by Schultz, because nonspecific cleavage events are common; the specificity of the enzyme-based systems was artificially increased by lowering the temperature below physiologically relevant values (i.e. to 0ºC).

Considerable art has been developed on cleavage of RNA utilizing enzymes and ribozymes. At present the art is void of a teaching using metal complexes which cleave RNA hydrolytically at a physiologically relevant pH and temperature as synthetic analogs for enzymes or ribozymes to obtain sequence-directed hydrolysis of RNA. Sequence-directed RNA hydrolysis and RNA cleavage are highly desirable today in order to prepare catalytic antisense oligodeoxynucleotides useful as a means for inhibiting the expression of specific genes. From several practical perspectives, the fragile, high molecular weight enzyme-oligonucleotide conjugates described by Schultz et al are at an extreme

disadvantage in comparison with the low molecular weight, stable, synthetic ribonucleases of this

invention. These practical points include the ability to prepare more than minute quantities; the ability to prepare high-purity material free from contaminating activities or unknown, inactive impurities; the

potential to survive in vivo conditions and to avoid immunological responses; and the ability to avoid

nonspecific hydrolysis of both DNA and RNA. The art is also void of a teaching using imidazole groups attached to nucleosides, nucleotides and oligodeoxynucleotides as synthetic analogues for enzymes or ribozymes for the catalytic cleavage of RNA to obtain sequence-directed cleavage of RNA. Such RNA hydrolysis and cleavage are necessary to provide a basis for catalytic antisense drug development.

STATEMENT OF THE INVENTION

This invention is directed to the hydrolytic cleavage of RNA at physiologically relevant conditions. The underlying basis of this invention is the use of metal complexes which perform as synthetic analogs for enzymes or ribozymes in the hydrolysis of RNA. This invention is also directed to the cleavage of RNA by nucleosides, nucleotides and oligodeoxynucleotides containing two or more imidazole groups attached via an appropriate linker, to the cleavage of RNA by a

combination of two oligodeoxynucleotides each containing at least one imidazole group attached via an appropriate linker, and to the cleavage of RNA by an imidazole group attached via an appropriate linker to a nucleoside, nucleotide or oligodeoxynucleotide in the presence of an imidazole group in solution. The imidazole groups perform as synthetic analogs for the active sites of enzymes or ribozymes in the cleavage of RNA. Conjugate as used herein means a compound comprised of a metal complex covalently linked to a nucleoside or nucleotide or a compound comprised of two or more imidazole groups covalently linked to a nucleoside or nucleotide, or a combination of two or more nucleosides or nucleotides each having one or more imidazole groups covalently linked thereto. Oligodeoxynucleotide conjugate as used herein means a compound comprised of a metal complex covalently linked to an oligodeoxynucleotide or to a compound comprised of one or more imidazole groups covalently linked to an oligodeoxynucleotide, or a combination of two or more oligodeoxynucleotides each having one or more imidazole groups covalently linked thereto. The term imidazole group as used herein includes imidazole and analogs of imidazole, including nitrogen-containing compounds which retain the essential properties of the imidazoles, so that they may function as either acids, bases or both, in either the Lewis (Cotton and Wilkinson, Advanced Inorganic Chemistry. 1988, Wiley, NY, p36); Orchin et al (The Vocabulary of Organic Chemistry. Wiley, 1980, p248); or Br∅nsted

(Orchin et al, The Vocabulary of Organic Chemistry.

Wiley, 1980, p249) definitions of the terms.

A first aspect of this invention is directed to the discovery of metal complexes useful for promoting RNA hydrolysis. A second aspect of this invention is directed to a conjugate which is active for RNA

hydrolysis comprised of a metal complex covalently linked to a nucleoside or nucleotide. A third aspect of this invention is directed to the sequence-directed hydrolytic cleavage of RNA by a metal complex covalently linked to an oligodeoxynucleotide. Another aspect of this invention is directed to the discovery of two or more imidazole groups covalently linked to nucleosides, nucleotides and oligodeoxynucleotides useful for promoting RNA cleavage. The oligodeoxynucleotide provides molecular recognition via Watson Crick base pairing to the target RNA sequence.

Accordingly, major objects of this invention are to provide for the hydrolysis of RNA at physiologically relevant conditions and for the cleavage of RNA. other objects of this invention include (l) the discovery of metal complexes which are effective for the hydrolysis of RNA, (2) the discovery that molecules containing two or more imidazole groups show great enhancement over mono-imidazole species for the cleavage of RNA, (3) the preparation of conjugates which retain RNA cleavage behavior, (4) the preparation of oligodeoxynucleotide conjugates effective for the sequence-directed

hydrolysis of RNA under physiologically relevant conditions and the sequence-directed cleavage of RNA. Other objects and advantages of this invention will become apparent upon further study of this disclosure and the appended claims.

DESCRIPTION OF THE DRAWINGS

The structures of the compounds identified below by bold numbers in parenthesis are shown in reaction "Schemes" 1-9.

In Figure 1 there is shown a typical example of Applicants' HPLC assay of the hydrolysis of RNA

[poly(A)₁₂.₁₈] by the metal complex, Zn-N-Me(CR). A, Time= 0 hours; B, Time = 18 hours.

In Figure 2 there is shown the titration of 3'-[4-[4'-methyl(2,2'-bipyridin)-4-yl]butyl-phosphate]-2'-deoxy-thymidine ammonium salt (5) with CuCl₂ forming 3'-[4-[4'-methyl(2,2'-bipyridin)-4-yl]butyl-phosphate]-2'-deoxy-thymidine ammonium salt copper(II) (6). This Figure depicts Applicants' Example IV and demonstrates the formation of a metal complex nucleotide conjugate in accordance with Applicants' ihyehtion.

In Figure 3 there is shown the hydrolytic cleavage of RNA [poly(A)_12-18] by compound (6). This Figure depicts Applicants' Example V and demonstrates that a metal complex linked to the 3' position of a nucleotide is capable of hydrolyzing RNA. A, Control reaction, time = 48 hours; B, Reaction of (6) with RNA, time = 48 hours.

In Figure 4 there is shown the hydrolytic cleavage of RNA [poly(A)_12-18] by 5'-[4-[4'-methyl(2,2'- bipyridin)-4-yl]butyl-phosphate]-2'-deoxy-thymidine triethylammonium salt copper(II) (12). This Figure depicts Applicants' Example VIII and demonstrates that a metal complex linked to the 5' position of a nucleotide is capable of hydrolyzing RNA. A, Control reaction, time = 48 hours; B, Reaction of (12) with RNA, time = 48 hours.

In Figure 5 is shown the hydrolytic cleavage of RNA [poly(A)_12-18] by 5-[3-[[2-[[4-[4'-methyl[2,2'-bipyridin]-4-yl]-1-oxobutyl]amino]ethyl]amino]-3-oxopropyl]-2'-deoxy-uridine copper(II) (17). This

Figure depicts Applicants' Example XI and demonstrates that a metal complex linked to the base portion of a nucleoside is capable of hydrolyzing RNA. A, Control reaction, time = 48 hours; b, Reaction of (17) with RNA, time = 48 hours.

In Figure 6 there is shown the reaction of the Cu(bpy)²⁺ complex with both DNA [poly(dA)_12-18] and RNA [p-oly(A)_12-18]. This Figure depicts Applicants' Example II and demonstrates that the observed cleavage of RNA by the Cu(bpy)²⁺ complex is hydrolytic in nature and not oxidative. A, Control reaction with DNA, time - 18 hours; B, Reaction of the Cu(bpy)²⁺ with DNA, time = 18 hours; c, Control reaction with RNA, time = 18 hours; D, Reaction of the Cu(bpy)²⁺ complex with RNA, time = 18 hours.

In Figure 7 there is shown the densitometry results of polyacrylamide gel electrophoresis analysis of the sequence-directed hydrolysis of tRNA^Tyr by the oligodeoxynucleotide-Cu(bpy)²⁺ conjugate (32). This Figure depicts Applicants' Example XV showing Densitometry scans of the polyacrylamide gel of the reaction of (32) with tRNA^Tyr after 17 hours under the conditions described in Example XV and of the control reaction. A, Cleavage Reaction: 1.29μM tRNA^Tyr, 6.4 M (31), 12.9μM Cu(trpy)²⁺, 227μM Cu(SO₄), 50mM NaCl and 50mM Tris buffer pH = 7.8; Control Reaction: 1.29 M tRNA^Tyr, 12.9 M Cu(trpy)²⁺, 227 M Cu(SO₄), 50mM NaCl and 50 mM Tris buffer pH = 7.8; B, Cleavage Reaction: 1.29μM tRNA^Tyr, 6.4 M (31), 12.9μM Cu(trpy)²⁺, 227μM Cu(SO₄), 50mM NaCl and 50mM Tris buffer pH = 7.8; Control Reaction: 1.2μM tRNA^Tyr, 12.9μM CU(trpy)²⁺, 227μM Cu(SO₄) and 6.4μM 14mer-oligodeoxynucleotide 5'-HO-TGACGGCAGATTTA-OH-3'.

In Figure 8 is shown the structure and identity of compounds known to Applicants which do not show RNA hydrolysis according to this invention.

In Figure 9 there is shown the autoradiograph which depicts the cleavage of ³²P labeled RNA by compound (5A) and that compound (6λ) is ineffective at cleaving RNA. Lane #l, RNA control t=2 hours; Lane #2 through 6, Reaction of RNA with 1 mM (5A) ; Lane #2 , t=0 hours; Lane #3, t=0.5 hours; Lane #4, t-1 hour; Lane #5 , t=1.5 hours; Lane #6 , t=2.0 hours; Lane #l and #8, reaction of 2mM (6A) with RNA; Lane #7, t*0 hours; Lane #8, t=2 hours.

In Figure 10 there is shown a schematic view of the use of two oligodeoxynucleotide conjugates, labeled antisense Probe 1 and Probe 2, juxtaposed in a manner to enhance cleavage of RNA.

Scheme 1 depicts the synthesis of compound (5) as described in Applicants' Example III.

Scheme 2 depicts the synthesis of compound (11) as described in Applicants' Example VI.

Scheme 3 depicts the synthesis of compound (16) as described in Applicants' Example IX.

Scheme 4 depicts the synthesis of compounds (20) and (23) as described in Applicants' Example XII.

Scheme 5 depicts the synthesis of compound (30) as described in Applicants' Example XIV. Scheme 6 depicts the sequence-directed cleavage of tRNA^Tyr by compound (32) as described in Applicants' Example XV.

Scheme 7 depicts the synthesis of compound (5A) as described in Applicants' Example XVI.

Scheme 8 depicts the sequence-directed cleavage of RNA by compound (5A) as described in Applicants' Example XVII.

Scheme 9 depicts the synthesis of compound (12A) as described in Applicants' Example XVIII.

SUMMARY OF THE INVENTION

The hydrolytically effective oligodeoxynucleotide conjugates of this invention are comprised of a desired organic molecule, herein referred to as the ligand, a metal ion, which imparts the hydrolytic activity, and a desired oligodeoxynucleotide. The effective conjugates of this invention are comprised of two or more imidazole groups which impart the RNA cleavage activity, and one or more desired nucleosides, nucleotides or oligodeoxynucleotides.

In one aspect Applicants' invention is based on metal complexes which are effective for RNA hydrolysis, and the preparation of such metal complexes covalently linked to nucleosides, nucleotides and oligodeoxynucleotides. The metal complexes covalently linked to the nucleosides, nucleotides and oligodeoxynucleotides distinguishes Applicants' invention from the speculation of the C. A. Stein et al and the teaching of the P. G. Schultz et al references described above. Certain compounds of the type proposed by Stein et al, comprised of imidazole attached to nucleosides and oligodeoxynucleotides, were prepared and found not to be effective for RNA hydrolysis under the criteria of Applicants' invention. Such compounds and their lack of RNA hydrolysis activity are shown below in Table II as compounds (24), (25) and (26).

Agents as used herein means Applicants' synthetic RNA hydrolysis compounds comprising a metal and a ligand, or metal complex, covalently linked to an oligodeoxynucleotide and conjugates and oligodeoxyconjugates as defined herein. The oligodeoxynucleotide provides sequence-directed recognition of RNA targets under physiologically relevant conditions. The agents of this invention are effectively artificial enzymes which mimic natural ribonucleases and ribozymes. These agents possess several advantages over ribonucleases and ribozymes in applications where sequence-directed RNA hydrolysis is desired. Such advantages include (1) enhanced specificity over ribonucleases, (2) increased chemical stability over ribozymes, (3) ease of

production and isolation by standard chemical

techniques, (4) the ability to design sequence

specificity towards any targeted RNA strand, (5) low molecular weight, (6) drug delivery and (7) ability to control hydrolytic activity by altering the nature of the metal complex. These are important aspects of

Applicants' invention which permits the practical application of sequence-directed RNA hydrolysis and cleavage. These aspects of Applicants' invention provide considerable novelty and advantages over the prior art teachings, such as the University Patents, Inc. PCT Patent Application and the P. G. Schultz et al and C. B. Chen et al references, described above.

The nucleic acid hydrolysis compounds of Schultz et al differ from Applicants' invention in several import aspects. The nucleic acid cleavage behavior taught by Schultz et al is provided by an enzyme, not the synthetic small molecule hydrolysis agents

(artificial enzymes) used by Applicants. The enzymes are subject to proteolytic degradation by other enzymes. Staphylococcal nuclease is dependant on added calcium for its activity. Ribonuclease S is a noncovalent complex comprised of the S-protein and S-peptide derived from ribonuclease A. This complex is subject to

dissociation, which results in loss of cleavage efficiency and specificity. Oligodeoxynucleotidestaphylococcal nuclease conjugates were shown to cleave DNA as well as RNA; thus, they lack the specificity of Applicants' agents for RNA hydrolysis and cleavage alone. This high activity limits the specificity of the enzyme-based systems developed by Schultz et al because nonspecific cleavage events are common. The specificity of these enzyme-based systems was artificially increased by lowering the temperature below physiologically relevant values (i.e. to 0ºC).

From several practical perspectives, the fragile, high molecular weight enzyme-oligodeoxynucleotide conjugates described by Schultz et al are at an extreme disadvantage in comparison with Applicants' low

molecular weight, stable, synthetic ribonuclease

analogs.

Several practical points of Applicants' invention include the ability to prepare more than minute

quantities of the agents; the ability to prepare highpurity material free from contaminating activities or unknown inactive impurities; the potential to survive in vivo conditions and to avoid immunological responses and the ability to avoid nonspecific hydrolysis of both DNA and RNA.

Applicants' use of hydrolysis and use of two or more imidazole groups as the chemical reaction that cleaves RNA provides several advantages over the prior art, such as the non-selective oxidative cleavage of both RNA and DNA taught by Chen et al. Applicants' hydrolysis agents are active at pH 7 which is consistent with the conditions inside living cells. Since DNA is chemically hydrolyzed at a considerably slower rate than RNA, the sequence-directed RNA hydrolysis using

Applicants' oligodeoxynucleotide conjugates will not cleave their own oligodeoxy- nucleotide components at an appreciable rate. See Applicants' Example II below.

The term oligodeoxynucleotides used herein includes oligodeoxynucleotides and oligodeoxynucleotide analogs that are. effective at molecular recognition by, for example, Watson-Crick or Hoogsteen base-pairing. Examples of such oligodeoxynucleotide analogs include those with nonionic internucleotide linkages such as alkylphosphotriesters, alkylphosphonates and

alkylphosphoramidates (as described by P. S. Miller, Oligodeoxynucleotides Antisense Inhibitors of Gene Expression, J. S. Cohen, Ed. CRC Press, Boca Raton, Florida, 1989, Chapter 4 and references therein) and compounds with sulfur-containing internucleotide linkages such as phosphorothioates and phosphorodithioates (as described by C. A. Stein et al, ibid, Chapter 5 and references therein), and alphaoligodeoxynucleotides (as described by B. Rayner et al, ibid, Chapter 6 and references therein). Other

oligodeoxynucleotide analogs which may be suitable include those with internucleotide linkages such as carbonate, acetate, carbamate, dialkyl and diarylsilyl groups.

Metal compounds applicable to this invention are those metal complex conjugates and oligodeoxynucleotide conjugates which are soluble in water at a neutral pH and are functionally effective for the hydrolytic cleavage of RNA under physiologically relevant

conditions. In their active forms, the metal complexes which hydrolyze RNA may contain hydroxyl or aquo ligands or both. These active forms may be derived in a

standard fashion from complexes which contain ancillary ligands such as, chloride, bromide, iodide, perchlorate, nitrate, sulfate, phosphines, phosphites and other standard mono- and bidentate ligands. The metal in the metal complexes may be any metal which is effective in hydrolyzing RNA. Typical metals include copper, zinc, cobalt, nickel, palladium, lead, iridium, manganese, iron, molybdenum, vanadium, ruthenium, bismuth,

magnesium, rhodium, uranium and the Lanthanide metals.

In order to provide the art a method of

determining the applicable agents, such as metal complexes and conjugates of this invention, Applicants' have developed an assay for monitoring the hydrolysis of RNA under physiologically relevant conditions (7.1 pH and 37ºC).

In another aspect Applicants' invention is based on (1) the use of two or more imidazole groups for RNA cleavage, and (2) the preparation of conjugates

containing such imidazole groups covalently linked to nucleosides, nucleotides and oligodeoxynucleotides.

Certain compounds of the type proposed by Stein et al, comprised of a single imidazole attached to nucleosides and oligodeoxynucleotides, were prepared and found not to be effective for RNA cleavage under the criteria of Applicants' invention.

APPLICANTS' ASSAY FOR HYDROLYSIS OF RNA

A mixture of adenylic acid oligomers 12 to 18 nucleotides in length [poly(A)_12-18] is used as the assay substrate. Ion exchange HPLC is used to resolve the individual cleavage products from the substrate

fragments. A compound is determined to be active if it shows hydrolytic degradation of the substrate, as illustrated in Figure 1, to an extent greater than that which is observed for a control reaction run under identical conditions in the absence of a cleavage agent. The extent of reaction is determined from the ratio of the integration of substrate peak at time = 0 hour and time = 18 hours.

HPLC analysis is performed with a Waters 600 multisolvent delivery system and a 490 programmable multiwavelength detector. Data is acquired on a NEC APC IV Advanced Personal Computer using Waters Maxima 820 software. With this system it is possible to determine the area under all the substrate peaks. Extensive standard precautions need to be taken to avoid RNase contamination: all buffers are made with diethylpyrocarbonate treated water (0.1% vol./vol.) and the reactions are run in sterilized polypropylene tubes. Typical stock solutions of RNA [poly(A)_12-18] having an adenosine concentration of 761μM are prepared by dissolving 10 units of the RNA in 20mM HEPES buffer pH = 7.1. HPLC analyses are run on a 7μM Nucleogen DEAE 60- 7 with an elution gradient of 0-15 min. 25% B, 15-45 min. 60% B, 45-60 min. 100% B; using Solvent A = 20mM KH₂PO₄, 20% acetonitrile, pH - 5.5; and Solvent B = Solvent A + 1M KCl.

The combination of agents applicable and useful in this invention are those which functionally promote RNA hydrolysis as determined by this assay. The above described assay is not to be considered a limitation on Applicants' invention. It is to be understood that other assays can be developed and used to determine the effectiveness of agents for the hydrolysis of RNA in accordance with this invention.

A further check for the effectiveness of the metal complexes for hydrolyzing RNA is the formation of a conjugate. In forming such conjugates, the selected ligand may first be covalently linked to the desired nucleoside or nucleotide and then the selected metal ion attached to the ligand. Alternatively, the intact selected metal complex may be covalently linked to the nucleoside or nucleotide. The ligand or intact metal complex may be covalently linked to the nucleoside or nucleotide at any location. The details of forming specific conjugates are fully described in Applicants' Examples.

Likewise, in preparing the oligodeoxynucleotide conjugates of this invention, the selected ligand may first be covalently linked to the desired oligodeoxynucleotide and then the selected metal ion attached to the ligand. Alternatively, the intact selected metal complex may be covalently linked to the oligodeoxynucleotide. The ligand or metal complex can be covalently linked to the oligodeoxynucleotide at any location. The details of forming a specific

oligodeoxynucleotide conjugate is fully described in Applicants' Example XIV. EXAMPLES

The following Examples illustrate this invention (its compositions, processes and utility) with relation to specific metals, imidazole groups, ligands,

nucleosides, nucleotides and oligodeoxynucleotides.

Specifics set forth in these Examples are not to be taken as limitations on the scope of the invention or to the applicable agents, elements or features of the invention.

EXAMPLE I

This Example shows how metal complexes and other compounds are screened for RNA hydrolysis activity.

Stock solution (lmM) of various transition metal complexes (shown in Table I) were prepared in 20mM HEPES buffer pH - 7.1. The assay mixture in a final volume of 1.5mL contained 133μM metal complex, 63μM poly(A)_12-18 and 20mM HEPES buffer. At time - 0 hours a 200μL of the mixture was removed and analyzed by Applicants' Assay. The reaction mixture was then incubated at 37ºC. for 18 hours after which time a second 200μL was removed and assayed. Summarized in Table I are the RNA hydrolysis active and inactive transition metal complexes and corresponding cleavage obtained as determined by

Applicants' Assay.

TABLE 1

Active % Cleavage Inactive % Cleavage

Cu(trpy)²⁺ 75 Cu(bpy)₂ ²⁺ 0

cu(bpy)²⁺ 43 Ni-(CR)²⁺ 0

Zn-N-Me-(CR)²⁺ 20 [CuCR(CH₂)₃CuCR]⁴⁺ 0

Cu-2,2-CR²⁺ 22 Cu(EDTA) 0

Zn(EDTA) 0

Zn(NTA)1^-1- 0 Abbreviations: trpy - 2 , 2':6',2"-terpyridine; bpy - 2,2'-bipyridine; N-Me-(CR) = 7-(N-methyl)-2,12-dimethyl- 3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1

(17),2,11,13,15-pentaene; CR = 2,12-dimethyl-3,7,11,17-tetraazabicyclo [11.3.1]heptadeca-1 (17),2, 11,13,15-pentaene; 2,2-(CR) = 2,10-dimethyl-3,6,9,12-tetraazabicyclo[9.3.1]pentadeca-1 (15),2,10,12,15-pentaene; EDTA = ethylenediaminetetraacetic acid; NTA = nitrilotriacetic acid; CR(CH₂)₃(CR) = 7,7' (1,3-propanediyl)-bis[2,12-dimethyl-3-7,11,17-tetraazabicyclo[11.3.1]heptadeca-1 (17),2,11,13,15-pentaene.

Summarized in TABLE 2 are compounds known to Applicants which are found not to be effective in RNA hydrolysis according to Applicants' Assay. TABLE 2

Compound % Cleavage

5 0

11 0

16 0

24 0

25 0

26 0

27 0

The identity and structure of the compounds in Table 2 are shown Figure 8. EXAMPLE II

This Example shows that under conditions where a Cu(bpy)²⁺ complex substantially hydrolyzes RNA, it does not degrade DNA.

The observed cleavage of RNA by various Cu(bpy)²⁺ complexes was hydrolytic and not oxidative. This was demonstrated by comparing the reactivity of the Cu(bpy)²⁺ complexes with both DNA and RNA. A stock solution of DNA [poly(dA)_12-18] was prepared by dissolving 25 units of the DNA in l.OmL of 20mM HEPES buffer pH - 7.1. The reaction mixture contained in a total volume of 1.5mL, 63μM of the DNA, 157μM bipyridine, 157μM CuCl₂ and 20mM HEPES buffer. The solutions were incubated at 37'C for 48 hours after which time they were assayed by ion exchange HPLC. Identical conditions were used in the reaction of the Cu(bpy)²⁺ complex with RNA [poly(A)₁₂₊₁₈].

Figure 6 contains the HPLC analysis of the reactions of the Cu(bpy)²⁺ complexes with the DNA and RNA. After 48 hours the RNA is extensively hydrolyzed. By contrast, the DNA substrate showed no evidence of degradation. It has been reported that both RNA and DNA are oxidatively cleaved by 1,10-phenathroline-copper(II) at similar rates (C. B. Chen et al, J. Am. Chem. Soc. 1988, 110, 6570-6572). Consequently, one would expect to see extensive cleavage of the DNA by the Cu(bpy)²⁺ complex if an oxidative mechanism was operative.

EXAMPLE III

This Example shows the attachment of bipyridyl ligand (bpy) to the 3' position of 2'-deoxy-thymidine nucleotide as outline in Scheme 1.

5'-O-DMT-2'-deoxy-thymidine-3'-O-¶-cyanoethyl N,N-diisopropyl phosphoramidite (1) (0.4 gm , 0.537 mmol) was dissolved in anhydrous CH₃CN (5mL) under N₂ and tetrazole (0.112 gm., 1.61 mmol) was added. DMT is 4,4'-dimethoxytrityl. The resulting mixture was stirred at room temperature for 15 minutes. An acetonitrile solution (5mL) of 4'-methyl-4-(hydroxybutyl)-2,2'- bipyridine (2) (0.130 gm. , 0.540 mmol) was added and after 1 hr. the mixture was concentrated in vacuo to yield a glass of compound 5'-O-DMT-2'-deoxy-thymidine- 3'-O-[4-[4'-methyl(2,2'-bipyridin)-4-yl]butoxy]-¶- cyanoethoxyphosphine (3). Compound (3) was dissolved in CH₂Cl₂ (3mL), cooled to 0ºC in an ice bath and t-BuOOH in 2,2,4,4-tetramethylpentane (0.643 mL, 1.93 mmol) was added. After 20 min. the mixture was concentrated invacuo to yield a glass of 5'-O-DMT-3'-[4-[4'-ethyl(2,2'-bipyridin)-4-yl]butyl-1-cyanoethyl phosphate]-2'-deoxythymidine (4). Compound (4) (0.382 gm., 0.432 mmol,

80.4%) was eluted from an Alumina column (neutral) using 5% MeOH in CH₂Cl₂.

Compound (4) (0.382 gm. , 0.432 mmol) was dissolved in aqueous NH₃ (10mL) and left to stir at room temperature for 6 hours. The mixture was concentrated in vacuo using EtOH to remove water. The residue was treated with 25% CF₃COOH in CH₂Cl₂ (5mL) for 15 minutes. After removing the volatile components in vacuo the residue was dissolved in water (lOmL) and the aqueous layer washed with ether (2x5mL) and CH₂CL₂ (2×5mL) . The aqueous layer was concentrated in vacuo to yield the desired deprotected nucleoside 3 '-[4-[4'-methyl(2,2'-bipyridin)-4-yl]butyl-phosphate]-2'-deoxy-thymidine ammonium salt (5) (0.192 gm., 0.354 mmol, 82%).

EXAMPLE IV

This Example shows the titration of compound (5) with CuCl₂ to form 3'-[4-[4'-methyl(2,2'-bipyridin)-4-yl]butyl-phosphate]-2'-deoxy-thymidine ammonium salt copper(II) (6) (Figure 2).

A 1mL aliquot of a 53.4μM solution of compound

(5) in 20mM HEPES buffer having a pH of 7.1 is placed in a quartz cuvette and aliquots of a 1.178mM stock

solution of CuCl₂ in water was added. Changes in the visible spectrum were monitored between the wavelength of 240 and 380nm. The addition of CuCl₂ causes the band at 276nm to decrease with concomitant increase in absorbances at 302 and 312nm. The changes occur with an isosbestic pint at 289nm and are characteristic of coordination of Cu^2* to bipyridine.

A similar titration with the solution of 3'-thymidine monophosphate without the bipyridine ligand showed no changes in the visible spectrum over the noted region.

EXAMPLE V

This Example shows the hydrolysis of RNA

[poly(A)_12-18] by a nucleotide covalently linked through the 3' position to a metal complex (Figure 3).

For the reactions of metal complex-nucleotide (nucleoside) conjugates. Applicants' HPLC Assay

described above was modified. These compounds are not as reactive as the free metal complexes, thus, the reaction time was extended to 48 hours.

In a total of 500μL, the reaction mixture contained 157μM of compound (5), 63μM RNA, 157μM Cu(SO₄) and 20 mM HEPES buffer pH= 7.1. Using this mixture, compound (6) was formed under the conditions set forth in Example IV. At time zero, a lOOμL aliquot of the reaction mixture was removed and immediately analyzed by Applicants' HPLC Assay. The reaction mixture was incubated at 37ºC for 48 hours after which time a second aliquot was removed and assayed. It was found that the RNA substrate was clearly hydrolyzed by compound (6) (Figure 3).

A control reaction carried out in the same manner except in the absence of the Cu(SO₄) showed no hydrolysis of the RNA even after the 48 hour incubation.

EXAMPLE VI

This Example shows the attachment of bipyridyl ligand (bpy) to the 5' position of 2'-deoxy-thymidine nucleotide as outlined in Scheme 2.

Preparation of 5'-[4-[4'-methyl(2,2'-bipyridin)- 4-yl]butyl]-methylphosphate-3'-O-acetyl-2'-deoxythymidine (10): a mixture of 4-[4'-methyl(2,2'- bipyridin)-4-yl]butyl-methyl-N,N-diisopropyl

phosphoramidite (8) (0.101 gm., 0.25 mmol) and tetrazole in lmL of THF was stirred at room temperature for 10 minutes. 3'-O-acetyl-2'-deoxythymidine (7) (0.071 gm., 0.25 mmol) dissolved in CH₂Cl₂ (lmL) was added to the reaction mixture and the solution was left stirring for 60 minutes. The mixture was then filtered to remove tetrazole which precipitated out. The solid was washed with acetonitrile (5mL) and CH₂Cl₂ (5mL) and concentrated to yield 5'-0-[ [4-[4'-methyl(2,2'-bipyridin)4-yl] butoxy]methoxy]-3'-O-acetyl-phosphine-2'-deoxy-thymidine (9) as a glass. The compound (9) glass was dissolved in MeOH (1mL), cooled to 0ºC and a 3M solution of t-butyl hydroperoxide in 2,2,4,4-tetramethylpentane (0.3 mL, 0.9 mmol) was added to the stirred reaction mixture. After 15 min. the ice bath was removed and the mixture stirred at room temperature for 20 minutes. The mixture was concentrated to a glass and flash chromatographed on an alumina column (TLC grade). The desired compound (10) (0.071 gm., 0.118 mmol, 47%) eluted off the column using a gradient of CH₂Cl₂ to 10% MeOH in CH₂Cl₂ as an eluant.

Preparation of 5'-[4-[4'-methyl(2,2'-bipyridin)-4-yl]butyIphosphate]-2'-deoxy-thymidine triethylammonium salt (11): to compound (10) (0.071 gm., 0.118 mmol) dissolved in CH₂Cl₂ (3mL), 25% NaOMe in MeOH (0.05 mL, 0.12 mmol) was added. The mixture was stirred for 15 min. at room temperature. After 15 min. the reaction was quenched with glacial acetic acid (0.06 gm., 0.12 mmol). Dichloromethane (50mL) was added and the organic layer washed with saturated NaHCO₃ solution (2×20mL) and water (10mL). The organic layer was dried over

anhydrous Na₂S0₄ and concentrated in vacuo to a glass (0.064 gm., 0.114 mmol, 97%). The glass was dissolved in 0.5 mL thiophenol:dioxane:triethylamine (1:2:2), a commercial deprotection reagent by Sigma Chemicals, and left to stir for 90 minutes. The mixture was

concentrated in vacuo to a glass and the residue

dissolved in water (10mL). The aqueous layer was washed with petroleum ether (2×10mL) to remove traces of thiophenol. Final purification was carried out by RP C 18 Sep-Pak column and eluting the desired compound (11) (0.069 gm., 0.106 mmol, 90%) with H₂O:CH₃CN (4:1).

EXAMPLE VII

This Example shows the titration of compound (11) prepared in Example VI with CuCl₂ to form 5'-[4-[4'-methyl(2,2'-bipyridin)-4-yl]-butyl-phosphate]-2'-deoxythymidine triethylammonium salt copper(II) (12).

The procedure described in Example II was followed. Changes in visible spectrum, similar to those shown in Figure 3, characteristic of coordination of copper(II) to bipyridine were observed. Titration of thymidine-5'-monophosphate showed no changes in the visible spectrum over the range 240-380nm.

EXAMPLE VIII

This Example shows the hydrolysis of RNA

[poly(A)_12-18] by a nucleotide covalently linked through the 5' position to a transition metal complex.

An identical procedure was used as described in Example IV except that compound (12) was the hydrolysis agent (Figure 4).

EXAMPLE IX

This Example shows the attachment of bipyridyl ligand (bpy) to the 5- position of the uracil in a uridine nucleoside as outlined in Scheme 3.

Preparation of 5'-O-DMT-5-[3-[[2-[[4-[4'-methyl [2,2'-bipyridin]-4-yl]-1-oxobutyl]amino]ethyl]amino]-3- oxopropyl]-2'-deoxy-uridine (15): a solution of 5-[3- [(2-aminoethyl)amino]-3-oxopropyl]-5•-O-DMT-deoxyuridine (13) (0.322 gm, 0.5 mmol) in CH₃CN (5mL) and Et₃N (0.2mL) was cooled to 0ºC in an ice bath and 4-[3-carbo- 3-(p-nitrophenoxy)propyl]-4'-methy1-2,2'-bipyridine (14) (0.566 gm, 1.5 mmol) was added to the stirred reaction mixture. After 15 min. the ice bath was removed and the mixture was stirred at room temperature for 24 hours. The reaction mixture was diluted with 20mL CH₂Cl₂ and water (10mL). The aqueous layer was washed with CH₂Cl₂ (2×20mL). The dried (MgSO₄) organic layer was

concentrated in vacuo and flash chromatographed on an alumina (neutral) column eluting with a gradient of CH₂Cl₂ to 6% EtOH in CH₂Cl₂ to remove p-nitro-phenol. The desired product eluted off the column using EtOH along with C-3 bpy acid. Compound (15) (0.211 gm., 0.24 mmol, 45%) was purified by RP HPLC using a linear ternary gradient flowing at 6 mL/minute. Solvent A (0.1M)

[Et₃NH]OAc was kept constant while MeCN and H₂O were varied.

Preparation of 5-[3-[ [2-[[4-[4'-methyl[2,2'-bipyridin]-4-yl]-1-oxobutyl]amino]ethyl]amino]-3-oxopropyl]-2'-deoxy-uridine (16): a solution of the nucleoside (15) (0.150 gm., 0.17 mmol) in CH₂Cl₂ (5mL) was treated with 10% CF₃COOH in CH₂Cl₂ (5mL) for 15 minutes. The mixture was concentrated to a glass and dissolved in water (10mL). The aqueous layer was washed with CH₂Cl₂ (2×10mL) and compound (16) (0.093 gm., 0.16 mmol, 94%) was purified by RP HPLC using a linear ternary gradient flowing at 6 mL/minute. Solvent A (0.1M) [Et₃NH]OAc was kept constant while MeCN and H₂O were varied.

EXAMPLE X

This Example shows the titration of compound (16) with CuCl₂ to form 5-[3-[[2-[[4-[4'-methyl[2,2'-bipyridin]-4'-yl]-1-oxobutyl]amino]ethyl]amino]-3-oxopropyl]-2'-deoxy-uridine copper(II) (17).

The procedure described in Example III was followed. Changes in visible spectrum similar to those shown in Figure 2 and characteristic of coordination of copper(II) to bipyridine were observed. Titration of uridine showed no changes in the visible spectrum over the range 240-380nm.

EXAMPLE XI

This Example shows the hydrolysis of RNA

[poly(A)_12-18] by a metal complex covalently linked through the 5- position of uracil in a uridine

nucleoside.

An identical procedure was used as described in Example IV except that compound (17) was the hydrolysis agent. Hydrolysis of the RNA is evident as shown in Figure 5.

EXAMPLE XII

This Example shows the preparation of various terpyridine (trpy) derivatives (Scheme 4) which can be attached to nucleotides as described in Examples IV and V and which have been previously shown in Example I to be active RNA hydrolysis catalysts.

Preparation of 4'-(3-formylpropyl)-2,2':6',2"-terpyridine (19) : a 100 mL three necked RB flask, equipped with a rubber septum, a teflon coated stir bar and a gas inlet adaptor was flushed with N₂. 4'-methyl-2,2':6',2"-terpyridine (18) (0.494 gm., 2 mmol),

prepared by literature methods (see K. T. Potts, et al, J. Am. Chem. Soc , 1987, 109, 3961-3967) was dissolved in dry THF (10mL) and was syringed into the flask. The reaction mixture was cooled to -78ºC and LDA (1.6 mL, 2.4 mmol) was added via syringe. The resulting dark brown mixture was stirred for 2 hr. at -78ºC. 2-(2-bromoethyl)-1,3-dioxolane (0.434 mL, 2.4 mmol) was syringed into the reaction mixture, stirred for 1 hr. at -78ºC and allowed to warm to room temperature overnight. The mixture was poured over 10 ml brine and the aqueous layer was extracted with CH₂Cl₂. The extracts were dried over MgSO₄ and evaporated to dryness to yield the crude acetal. The acetal was hydrolyzed with 1M HCl (10mL) by heating to 50-60ºC for 2 hours. The solution was then neutralized with aqueous NaHCO₃ and extracted with

CH₂Cl₂. The extracts were dried over MgSO₄ and

evaporated to dryness to yield the crude aldehyde.

Purification by flash chromatography (neutral alumina, CH₂Cl₂ elution) gave pure aldehyde (19) (0.339 gm., 1.12 mmol, 56%).

Preparation of 4'-(4-hydroxybutyl)-2,2':6',2"- terpyridine (20): the aldehyde (19) (0.303 gm., 1 mmol) was dissolved in absolute ethanol (5mL) and sodium borohydride (0.05 gm., 1 mmol) was added at room temperature. After stirring for 30 min. the mixture was poured into 10mL brine and extracted with CH₂Cl₂

(3×10mL). The extracts were dried over MgSO₄ and evaporated to dryness to yield the desired alcohol (20) (0.264 gm., 0.86 mmol, 86%).

Compound (20) is analogous to compound (2) in Scheme 1 and can be attached to the 3' position of thymidine in a similar fashion as described in Example II.

Preparation of 4'-(4-bromobutyl)-2,2':6',2"-terpyridine (21): the alcohol (20) (0.200 gm., 0.65 mmol) was dissolved in 5mL HBr (45%) and refluxed for 6 hours. After cooling to room temperature the mixture was poured over 20 gm. of crushed ice, basified with saturated aqueous solution of Na₂CO₃ and extracted with CH₂Cl₂. The extracts were dried over (MgSO₄) and evaporated to dryness to yield the bromo derivative (21) (0.186 gm., 0.51 mmol, 78%).

Preparation of 4'-(4-phthalimidobutyl)-2,2':6',2"-terpyridine (22): the bromo compound (21) (0.186 gm., 0.51 mmol) in DMF (2mL) was added to a suspension of potassium phthalimide (0.095 gm., 0.51 mmol) in DMF (lmL). The mixture was stirred for 2 hr. at 50-60ºC. After cooling the reaction mixture was poured into water (10mL) and the resulting mixture was thoroughly extracted with CHCl₃ (3×25mL). The organic layers were combined, washed with 20mL of 0.2 M NaOH, water (20mL) and dried over Na₂SO₄. Removal of solvent under reduced pressure gave a thick oil.

Recrystallization from ethanol gave compound (22) as a white crystalline solid (0.208 gm., 0.48 mmol, 95%) mp 128ºC.

Preparation of 4'-(4-aminobutyl)-2,2':6'2"-terpyridine (23): phthalimide derivative (22) (0.208 gm., 0.48 mmol) was suspended in 7mL EtOH and treated with hydrazine hydrate (88 mg., 0.48 mmol). The mixture was refluxed for 6 hr., cooled, to room temperature, poured into brine (10mL) and basified with 50% w/w NaOH to pH 12. The mixture was thoroughly extracted with CH₂Cl₂ (3×10mL). The organic layers were dried over Na₂SO₄. Removal of solvent under reduced pressure gave the desired product (23) (0.130 gm., 0.43 mmol, 89%).

Compound (23) can be attached to the 5' position of 2'-deoxy-thymidine by literature procedures (see B. C. F. Chu et al, DNA 1985, 4, 327-331).

EXAMPLE XIII

This Example shows a variety of nucleosides and nucleotides which have groups appended on the 3' and 5' position of 2'-deoxy-thymidine and 5- position uracil in 2'-deoxy-uridine and which are not active at hydrolyzing RNA [poly(A)_12-18] under the conditions of the HPLC assay (Table 2).

No hydrolysis of the RNA was observed with the compounds shown in Table 2 when assayed in the absence of Cu(SO₄) under the conditions described in Example IV.

EXAMPLE XIV

This Example shows the attachment of bipyridine ligand to a 14mer oligodeoxynucleotide (30) as shown in Scheme 5.

Preparation of 4-(3-carbo-N-hydroxysuccin- imidopropyl)-4'-methyl-2,2'-bipyridine (29): 4-(3-carboxypropyl)-4'-methyl-2,2'-bipyridine (28) (1.0 gm., 3.9 mmol) and N-hydroxysuccinimide (0.494 gm., 4.3 mmol) were dissolved in EtOAc (10ML) and the mixture was cooled to 0ºC in an ice bath. Compound (28) was

prepared in accordance with the teachings of L. Ciana et al, J. Org. Chem. 1989, 54, 1731-1735. Dicyclohexylcarbodiimide (DCC) (0.804 gm., 3.9 mmol) was added in small portions and the mixture was stirred at 0ºC for 30 minutes. The ice bath was removed and the mixture was allowed to stir at room temperature for 12 hours. The resulting precipitate was filtered off and the filtrate concentrated in vacuo. The residue was

dissolved in CH₂Cl₂ (100mL), washed with water (50mL) and dried over Mg(SO₄). The dried.organic extract was concentrated in vacuo to yield compound (29) (0.827 gm., 2.3 mmol, 59%) . Preparation of oligodeoxynucleotide-bipyridine conjugate (31) : to an aqueous solution (20mL) of the oligodeoxynucleotide (30) was added a solution of compound (29) in CH₃CN (20mL). The pH of the mixture was raised to 9.3 by the addition of Et₃N and the mixture was stirred overnight. The oligodeoxynucleotide-bipyridine conjugate (31) was purified by anion exchange HPLC.

EXAMPLE XV

This Example shows a sequence-directed cleavage of tRNA^Tyr by an oligodeoxynucleotide-bipyridine

copper(II) (32) complex in accordance with this

invention as outlined in Scheme 6.

A 10lμM stock solution of oligodeoxynucleotidebipyridine conjugate (31) was prepared by dissolving 6.1 units of compound (31) in 500μL of 20 mM HEPES buffer having a pH of 7.1. A 25.9μM stock solution of the tRNA^Tyr substrate was prepared by dissolving 10 Units of tRNA^Tyr in 500μL of 20 mM HEPES buffer having a pH of 7.1. The cleavage reaction contained in a total of 600μL, 1.29μM tRNA^Tyr, 12.9μM Cu(trpy)²⁺, 227μM Cu(SO₄), 6.4μM compound (31), 50mM NaCl and 50mM HEPES buffer having a pH of 7.8. Initially the tRNA^Tyr, compound (31), NaCl and buffer were combined and heated to 65*C for 4 min. in a water bath. The reaction was removed and

immediately placed on dry ice. The mixture was allowed to thaw at 0ºC after which time the Cu(SO₄) and the

Cu(trpy)^2* complex were added. Applicants have shown in Example III that the copper(II) coordinates to the bipyridine ligand exclusively forming in this case the oligodeoxynucleotide-metal complex conjugate (32). The reaction was heated at 37ºC and 100μL aliquots were removed at times - 0, 17 and 28 hours. Analysis of the aliquots by polyacrylamide gel electrophoresis revealed three distinct cleavage sites adjacent to the targeted sequence as shown in Figure 6. These bands appeared in a time-dependent fashion and control reactions were devoid or showed significantly reduced cleavage in these regions. The predicted position of RNA cleavage based on the hybridization of compound (32) to tRNA^Tyr would produce a fragment 51 nucleotides in length (Scheme 5). This fragment was observed. Two other fragments also appear from the reaction. These are attributed to cleavage at sites brought close to the reactive group in compound (32) due to three dimensional folding of the tRNA^Tyr molecule. Thus, sequence-directed cleavage of tRNA^Tyr was demonstrated.

EXAMPLE XVI

This example shows the synthesis of the diimidazole containing nucleoside (5A) , 5-[3-[[2-[[2-[[2-amino]-1-oxo-3-[1H-imidazol-4-yl]propyl]amino]-1-oxo-3-[1H-imidazol-4-yl]propyl] amino]ethyl]amino]-3oxopropyl]-2'-deoxy-uridine, as outlined in Scheme 7. The synthesis of compound (IA) has been previously described (Dervan et al., Proc. Natnl . Acad. Sci . USA 1985, 82, 968).

The nucleoside 5'-O-DMT-5-[3-[(2-aminoethyl)-amino]-3-oxopropyl]-2'-deoxy-uridine (IA) (1.288 g, 2.0 mmol) was dissolved in dry dichloromethane (10 mL) and was cooled to 0ºC in an ice bath. Fmoc-L-His(Tr)-O-pfp (3.16 g, 3.0 mmol) was added to the stirred reaction mixture. Triethylamine (0.28 ml, 2.0 mol) was added to the solution and the mixture was stirred at room

temperature for 8 hours. The reaction mixture was concentrated and purified by flash chromatography on a silica gel column eluting with a gradient of 100% CH₂Cl₂ to 12% EtOH in CH₂Cl₂. The nucleoside 5'-O-[Bis(4-methoxyphenyl)phenylmethyl]-5-[3-[[2-[[2-[[(9H-fluoren9-yl-methoxy)carbonyl]amino]-3-[l-(triphenyl methyl)- 1H-imidazol-4-yl]propyl]amino]ethyl]amino]-3- oxopropyl]-2'-deoxyuridine (2A) (1.94 g,1.56.mmol, 78%) eluted off the column using 10% EtOH in CH₂Cl₂.

The nucleoside (2A) (1.94 g, 1.56 mmol) dissolved in CH₂Cl₂ (10 mL) was treated for 3 hours at room temperature with Et₂NH (10 mL) and the mixture was concentrated to a glass. The residue was flash chromatographed on a silica gel column. The deprotected impurities were eluted off the column using CH₂Cl₂ and the nucleoside 5'-O-[Bis(4-methoxyphenyl)phenylmethyl]- 5-[3-[[2-[amino]-3-[1-(triphenylmethyl)-1H-imidazol-4- yl]propyl]amino]ethyl]amino]-3-oxopropyl]-2'-deoxyuridine (3A) (1.43 g, 1.4 mmol, 90%) was eluted off with 80% EtOH in CH₂Cl₂. A solution of (3A) (lg, 2.0 mmol) in dry dichloromethane (10mL) was cooled to O'C in an ice bath and Fmoc-L-His(Tr)-O-pfp (3.16 g, 3.0 mmol) was added to the stirred reaction mixture. Triethylamine (0.28 ml, 2.0 mol) was added to the solution and the mixture was stirred at room temperature for 8 hours.

The reaction mixture was concentrated and flash

chromatographed on a silica gel column eluting with a gradient of 100% CH₂Cl₂ to 15% EtOH in CH₂Cl₂. The nucleoside 5'-O-[bis(4-methoxyphenyl)phenylmethyl]-5- [3-[[2-[[2-[[2-[[(9H-fluoren-9-yl-methoxy)carbonyl]-amino]-1-oxo-3-[1-(triphenylmethyl)-1H-imidazol-4-yl]propyl] amino]-1-oxo-3-[1-(triphenylmethyl)-1H-imidazol-4-yl]propyl]amino]ethyl]amino]-3-oxopropyl]-2'-deoxyuridine (4A) (1.94 g,1.56 mmol, 72%) was eluted off with 12% EtOH in CH₂Cl₂, mp 156-8ºC.

The nucleoside (4A) (0.4 g, 0.246mmol) was dissolved in CH₂Cl₂ (5 ml) and was treated with

diethylamine (5mL) and left to stir for 9 hours. The mixture was concentrated and the residue flash

chromatographed on a silica gel column. The compound, eluted off the column using 10% NH₃ in EtOH was stirred with a solution of 15% CF₃COOH in CH₂Cl₂ (5 ml). After 30 minutes, the mixture was concentrated. The residue was suspended in CH₂Cl₂ (25 ml) and water (10 ml). The aqueous layer was cashed with CH₂Cl₂ (2x5 ml) and ether (2×5 ml) and concentrated to give the diimidazole nucleoside conjugate 5-[3-[[2-[[2-[[2-amino]-1-oxo-3-[1H-imidazol-4-yl]propyl]amino]-l-oxo-3-[1H-imidazol-4-yl]propyl]amino]ethyl]amino]-3-oxopropyl]-2'-deoxyuridine (5) (0.120 g, 0.194 mmols, 79%). EXAMPLE XVII

This example shows the cleavage of a 172mer RNA fragment by compound (5A) and that the mono-imidazole compound 5-[3-[[2-[[2-amino-3-(1H-imidazol-4-yl)-1-oxopropyl]amino]ethyl]amino]-3-oxopropyl]-2'-deoxyuridine (6A) (Bashkin, Gard, and Modak, J. Org. Chem. 1990, 55, 5125) does not hydrolyze the RNA fragment under identical reaction conditions (Figure 9).

Extensive precautions were taken to avoid RNase contamination in the hydrolysis reactions. All buffers were made with distilled-deionized water which was treated with diethylpyrocarbonate (0.1% vol/vol) and hydrolysis reactions were run in sterilized

polypropylene tubes. Analysis of the cleavage reactions were performed with denaturing polyacrylamide gel electrophoresis using standard techniques (D'Alessio, J. M. In Gel Electrophoresis of Nucleic Acids A

Practical Approach; D. Rickwood and B. D. Hanes Eds. IRL Press Limited: London 1982; p. 173-196.) Uniformly 32P radiolabeled RNA substrate was generated by runoff transcription with bacteriophage SP6 DNA-dependent RNA polymerase using standard techniques (Maniatis, T.;

Fritsch, E.; Sambrook, J. Molecular Cloning: A

Laboratory Manual ; Cold Spring Harbor Laboratory: New York, 1982). HEPES buffer, purchased from Sigma

Chemical Co, (St. Louis), was used without further purification. All electrophoresis reagents used were RNase free.

A stock solution of ³²P labeled RNA was prepared by dissolving approximately 40μg of RNA in 90 μL of 20mM HEPES buffer pH=7.1. Stock solutions of (5A), 4.9 mM, and (6A), 3.1 mM were prepared in 20 mM HEPES buffer. The control reaction (#l) contained in a total volume of 25 μL, 4.5 μg ³²P labeled RNA which was diluted to volume with HEPES buffer. The reaction (#2) with agent (5A) contained in a total volume of.90 μL, approximately 23 μg of ³²P labeled RNA and 1 mM compound (5A). The reaction (≠2) with agent (6A) contained in a total volume of 50 μL, approximately 9 μg of ³²P labeled RNA and 2 mM compound (6A) . All reactions were run at 50º C for a total of 2 hours after which time 20 μL was removed and immediately frozen on dry ice. In the case of reaction #l , a single point was taken at 2 hours. In the case of reaction #2, 20 μL aloquats were removed at time = 0, 0.5, 1, 1.5, and 2 hours. In the case of reaction #3, 20 μL aloquats were remove at t = 0 and 2 hours. The samples were loaded onto PAGE gels (15%, 7 M urea) and were run for 4 hours at 900 V. Gels were developed using standard autoradiography techniques (Maniatis, T.; Fritsch, E.; Sambrook, J. Moleculeur Cloning: A Laboratory Manual ; Cold Spring Harbor

Laboratory: New York, 1982.).

The results shown in Figure 9 clearly

demonstrate that reactions #2 shows nearly complete cleavage of RNA (Lanes #3 , 4, 5, 6,) while reactions #1 (Lane #1) and #3 (Lane #l and 8) are devoid of RNA cleavage. The fact that reaction #3 shows no cleavage even with 2 mM total imidazole concentration indicates that incorporating two imidazoles into the same

molecule, such as in compound (5A) , provides for

efficient cleavage of RNA.

EXAMPLE XVIII

This example shows the incorporation of

imidazole-nucleoside conjugates into di-, tri-, and oligodeoxynucleotides. These techniques may be applied for the incorporation of suitably protected conjugates into oligodeoxynucleotides.

Two complementary approaches were explored for the synthesis of imidazole-DNA conjugates: solution-phase phosphotriester chemistry and solid-phase

phosphoramidite chemistry. Both approaches employ the previously reported (Bashkin, J. K et al., J. Org. Chem. 1990, 55, 5125) compound (7A), which is a protected form of compound (6A). Thus, Scheme 8 shows the use of (7A) in the preparation of dinucleotide XpC (compound 10A), using the o-chlorophenylphosphate ester technique (Reese, C.B. Tetrahedron 1978, 34, 3143). Intermediate phosphodiester (8A) was prepared in 82% yield, and characterized by FABMS. The fully-protected

phosphotriester (9A) was prepared in 49% isolated yield; FABMS showed ions corresponding to M+3Li, M+2Li, M+Li, and M+3Li-Boc. After deprotection of (9A) and

purification of the product by reverse phase HPLC, the desired dinucleotide (10A) was obtained.

Scheme 9 shows the preparation of phosphoramidite (11A) and its use in the solid-phase synthesis of the dinucleotide XpT, compound (12A). Phosphoramidite (11A) has the characteristic ³¹P resonances at 149.4 ppm assignable to its two diastereomers; it was further characterized by FABMS and high resolution mass spectra. The ¹H NMR peak assignments of (15A) are given in the experimental section. To test its general

applicability, phosphoramidite 11 was then employed in the synthesis of (13A), an 11-mer oligodeoxynucleotide with the modified nucleoside at an internal position. The sequence prepared was 5'-TATCTTCTXAC-3', where X indicates the imidazole-containing nucleoside analogue.

Melting points were taken in Kimax soft glass capillary tubes on a Melt-Temp melting point apparatus equipped with a calibrated thermometer. All nuclear magnetic resonance spectra were recorded on Varian spectrometers at 25ºC. The ¹H and ¹³C spectra were measured on a VXR-400 while the ³¹P spectra were obtained on a XLA-200. The proton spectra resulted from Fourier transformation of the accumulated scans, consisting of 30016 data points in a 8 KHz spectral width with an acquisition time of 1.876 sec. Data were acquired with a 35º pulse (10 ms) and, where necessary, the strong H₂O resonance was presaturated for 3.0 s. The free

induction decays were zero filled to 32K and 0.5 Hz line broadening applied to the data prior to Fourier

transformation. The significant chemical shifts are reported in ppm (d units) downfield from TMS and the J_PC values are given in Hz. All compounds are more than 98% pure by ¹³C and ¹H NMR spectroscopy. Exchangeable protons are labeled (ex).

The high resolution mass spectra (HEMS) were recorded on a Finnegan/MAT90 spectrometer while the FAB+ low resolution spectra were run on a VG 40-250T

spectrometer. The FAB matrix was a saturated solution of Lil in 3-nitrobenzyl alcohol, which is especially useful for acid-labile, protected nucleosides. Thin layer chromatography was performed on Baker-Flex Silica gel IB2-F plates and spots visualized by irradiation with UV light (254 nm).

Preparative TLC was carried out by centrifugal TLC on a Chromatotron (Harrison Research) using silica gel plates (Analtech). Column chromatography was performed on Silica gel (Merck SG-60, 230-240 mesh). RP HPLC was carried out on a Alltech Econosil C18

preparative column (10m, 250 × 22.5 mm) for di- and tri-nucleotides using a linear ternary gradient flowing at 6 mL/ min: Solvent A (0.1M[Et₃NH]OAc) was kept constant at 25%, while B (MeCN) and C (H₂O) were varied as follows, where time is in min: (time,%B, %C) (0,5,70) (33,35,40) (45,70,5). Longer oligodeoxynucleotides were purified on a Nucleogen-DEAE 60-7 preparative column using a linear binary gradient flowing at 1.5 mL /min: Solvent A (80% 0.1M NaOAc, 20% MeCN) and Solvent B (20 % MeCN, 80% 1M LiCl and 0.02M NaOAc) were varied as follows, where time is in min: (time,%A, %B) (0,100,0) (33,0,100) (43,100,0). The HPLC was monitored

simultaneously at 260. and 400 nm.

The compounds p-nitrophenol, L-histidine (Sigma Chemicals), Fmoc-L-Lys(Boc)-Opfp (Pharmacia),

dicylohexyl carbodiimide, diethylamine,

diisopropylethylamine (Aldrich), Chloro-N,N-diisopropylamino-¶-cyanoethoxy-phosphine (ABN) were used without any further purification.

Preparation of 5 ' -O-[Bis (4-methoxyphenyl)-phenylmethyl ]-5- [ 3- [2- [ [ 2- [ [ (9H-fluoren-9-yl-methoxy) carbonyl] amino] -3- [ [ 1- (2.2-dimethyl- ethoxy) carbonyl1-1H-imidazol-4-yl]-1-oxopropyl]-amino]ethyl]amino-3-oxopropyl]-3'-[o-ehlorophenyl¬phosphodiester]-2'-deoxy-uridine (8A).

o-Chlorophenyl phosphorodichloridate (0.897 g, 3.66 mmol) was weighed into a two-necked pear-shaped flask and dissolved in acetonitrile (10 mL). 1,2,4-Triazole (0.556 g, 8.052 mmol) and triethylamine (1.02 mL, 7.32 mmol) were added to the reaction vessel, and the mixture stirred at room temperature for 20 minutes. The nucleoside (7A) was dissolved in acetonitrile (10 mL), and 1-Me-imidazole (0.1 mL, 4.88 mmol) was added to the stirred solution. This reaction mixture was added to the phosphorylating mixture in the pear-shaped flask and stirred at room temperature for 20 minutes. The reaction was monitored on TLC, and after all of the starting material was consumed, the mixture was quenched with triethylamine (3.06 mL, 21.96 mmol) and water (10 mL) to give a homogeneous solution. The solution was stirred for 10 minutes and then concentrated. The residue was dissolved in dichloromethane (25mL) and washed with sat. NaHCO₃ (25 mL). The aqueous layer was washed with dichloromethane (2×20mL), and the combined organic extracts were dried over MgSO₄ and concentrated to a glass. The glassy material was dissolved in dichloromethane (10mL) and precipitated from pet. ether (500mL). The solid phosphodiester (8A) (1.16 g, 0.91 mmol, 82%) was collected by centrifugation and dried in a vacuum desiccator. FABMS m/z 1171, (M - H) ; 1071, (M - H - Boc).

Preparation of Dimer X"pC- (9A).

The phosphodiester 8 (0.427 g, 3.36 mmol) was dissolved in dry pyridine (5 mL) and 4-N-3'-O-diacetyl- 2'-deoxycytidine (0.095 g, 3.05 mmol) was added to it and the pyridine removed under reduced pressure. The process of addition and removal of pyridine was carried out twice to remove traces of moisture. 1-(2- mesitylenesulfonyl)-3-nitro-1,2,4-triazole (0.361 g, 12.2 mmol) was then added to the solution of the two nucleosides and stirred at room temperature for 20-25 minutes. The mix:cure was then quenched with 1 mL saturated solution of NaHCO₃. Dichloro-methane (100mL) was added to the reaction mixture after 5 minutes, and the organic phase was washed with water (50 mL). The organic extracts were dried over MgSO₄ and concentrated to yield a glass. The glass was chromatographed over silica gel and the product (9A) (0.220 g, 1.5 mmol, 49%) eluted with CH₂Cl₂:EtOH : 90:10. FABMS m/z 1484, (M + 3Li); 1478, (M + 2Li); 1472, (M + Li); 1384, (M + 3Li - Boc).

Preparation of XPC (10A).

The fully protected dimer (9A) (0.220 g, 0.15 mmol) was treated with a freshly prepared solution of N¹, N¹, N³, N³ -tetramethylguanidine (0.33 M) and o-nitrobenzaldoxime in dry CH₃CN (1.5 mL). After 3 hours at room temperature the mixture was concentrated and the residue washed with ether. The solid was dissolved in aqueous NH₃ and stirred at room temperature for 24 hours. After concentrating the solution, the resulting solid was treated for 30 minutes with 50% CF₃COOH in

dichloromethane (10 mL). The fully deprotected

nucleoside was extracted with water (10 mL), and the aqueous layer was washed with diethyl ether (2×5 mL). The aqueous layer was evaporated to yield the

deprotected nucleoside (10A) (0.110 g, 0.143 mmol, 95% ). The sample was purified on a Alltech Econosil C18 preparative RP HPLC column. Retention time for (10A) (250 OD units) was 14.6 minutes on a C18 analytical column using the same linear ternary gradient, flowing at 1.5 mL/min. ³¹P NMR (D₂O) ppm 0.19 s; ¹H NMR (D₂O) d 6.25 (t, 1H, 1'X); 6.3 (t, 1H, 1'C); 2.45 (m, 2H, 2'X); 2.4 (m, 2H, 2'C); 4.8 (m, 1H, 3'X); 4.6 (m, 1H, 3'C); 4.1(m, 1H, 4'X); 4.0 (m, 1H, 4'C); 3.8 (m, 2H, 5'X); 4.2 (m, 2H, 5'C); 6.1 (d, 1H, H19); 7.9 (d, 1H, H18); 7.7

(S, 1H, H6), 2.4 (2 t'S, 4H, H7 S H8); 3.2 (2t's, 4H, H9 & H10); 4.25 (m, 1H, H11); 3.2 (m, 1H, H12); 7.3 (S 1H, H14); 8.4 (s, 1H, H15); ¹³C NMR (D₂O) ppm 154.2, 2CO; 168.3, 4CO; 116.2, 5C; 141.1, 6C; 25.8, 7C; 37.4, 8C; 41.8 & 41.2, 9C & 10C; 55.7, 11C; 30.3, 12C; 131.0, 13C; 120.6, 14C; 138.1, 15C; 178.3, 16C; 171.9, 17C; 144.9, 18C; 98.9, 19C; 159.3, 20C; 168.2, 21C; 88.3, l'X; 88.9, 1'C; 40.8, 2'X; 42.3, 2'C; 77.8, 3'X(J _CP = 5.1 Hz) ;

73.3, 3'C; 88.7(J _CP = 6.5 Hz), 4'X; 88.1, 4'C (J" _CP = 8.9 HZ); 64.0, 5'X; 67.8, 5'C (J _CP = 5.05 Hz) .

Preparation of 5'-O-[Bis(4-methoxyphenyl) phenyl methvn-5-[3-[2-[[2-[[(2.2-dimethylethoxy)carbonyl]-amipo]-3-[ [1-(2,2-di-pethylethoxy)carbonyl]-1H-imidazol- 4-yl]-1-oxopropyl]amino]ethyl]amino-3-oxopropyl]-2'-deoxy-uridine-3'-O-(N,N-diisopropyl-amino-¶-cyanpethoxy)phogphine (11A).

Chloro-N,N-diisopropylamino-¶- cyanoethoxyphosphme (0.158 g, 0.81 mmol) was weighed into an H-shaped Schlenk flask and dissolved in

acetonitrile (10 mL). Di-isopropylethylamine (0.196 mL, 1.52 mmol) was added to the reaction vessel and the mixture was stirred at room temperature for 20 minutes. The nucleoside (7A) (0.75 g), 0.76 mmol) was dissolved in acetonitrile and added to the phosphorylating mixture and left stirring for 30 minutes. The mixture was then filtered through the fritte to the other side of the Htube, removing the amine hydrochloride. The solid was washed with acetonitrile (2x10 mL) and the combined MeCN solutions were concentrated to yield a glass. The glass was then chromatographed on a silica gel chromatotron (2000M) . The phosphoramidite (11A) (0.721 g, 0.61 mmol, 80%) eluted out with CH₂Cl₂:EtOAc:Et₃N : 4.5:4.5:1. ³¹P NMR (CD₃CN) ppm 149.4. Two s's (diastereoisomers).

FABMS m/Z 1194, (M + 2Li) ; 1188, (M + Li); 1094, (M + 2Li -H - Boc); 994, (M + 3Li - H - Boc); exact mass found 1188.5789, calculated for C₆₀H₈₀N₉O₁₄PLi 1188.5722.

Preparatipn of XpT (12A).

The phosphoramidite (11A) was used on the

Pharmacia gene assembler to synthesize the dinucleotide 5'-O-DMT-X"pT which were fully deprotected and purified on an Alltech Econosil C18 preparative RP HPLC column. Retention time for (12A) (25 OD units) was 14.5 minutes on an analytical column using the same linear ternary gradient, flowing at 1.5 mL/min. 2H NMR (D₂O) d 6.3 (t, 1H, 1'X); 6.4 (t, 1H, 1'T); 2.55 (m, 2H, 2'X); 2.4 (m, 2H, 2'T); 4.65 (m, 1H, 3'T); 4.85 (m, 1H, 3'X); 4.2 (m, 1H, 4'X); 4.0 (m, 1H, 4'T); 3.85 (m, 2H, 5'X); 4.2 (m, 2H, 5'T); 7.75 (s, 1H, H6); 7.75 (s, 1H, H21); 2.4 (2 t's, 4H, H7 & H8); 3.3 ( m, 4H, H9 & H10); 4.35 (m, 1H, H11); 3.1 (m, 1H, H12); 7.2 (s, 1H, H14); 8.2 (s, 1H, H15); 1.95 (s, 3H, T-CH₃).

Preparation of 5'-HO-TATCTTCTXAC-OH-3' (13A). The phosphoramidite (14A) was used on the Pharmacia gene assembler to synthesize the 11-mer 5'HO-TpA'pT"pC'pTpTpC'pTpXpA'pC'-O-S-3' (10 mMole scale). The oligomer on the solid support was washed for 10 minutes with 10% CF₃COOH in CH₂Cl₂ to effect

detritylation and removal of the Boc groups.

Deprotection was completed with aqueous NH₃ (0.88 d), and the product was purified on a Nucleogen-DEAE 60-7 preparative HPLC column. Oligomer (13A) (90 OD units) eluted from an analytical ion exchange column at 23.5 minutes using the same solvent gradient flowing at 1.5 mL/min.

Claims

WHAT WE CLAIM IS:

1. The method of hydrolytically cleaving RNA under physiologically relevant conditions with a

compound selected from the group consisting of

nucleosides, nucleotides and oligodeoxynucleotides having attached thereto a metal complex effective for RNA hydrolysis.

2. The method of Claim 1 wherein said metal complex exhibits hydrolysis of RNA as shown by

Applicants' HPLC Assay.

3. The method of Claim 2 wherein said metal complex is attached to said compound at any location where chemical derivatization is possible.

4. The method of Claim 2 wherein said metal is selected from the group consisting of copper, zinc, cobalt, nickel, palladium, lead, iridium, manganese, iron, molybdenum, vanadium, ruthenium, bismuth,

magnesium, uranium, rhodium and the Lanthanide metals.

5. The method of Claim 2 wherein said metal is selected from the group consisting of copper, zinc and cobalt.

6. The method of Claim 2 wherein the ligand of said metal complex is selected from the group of

compounds consisting of 2,2':6',2"-terpyridine; 2,2'- bipyridine; 7-(N-methyl)-2,12-dimethyl-3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1 (17) ,2,11,13,15-pentaene; 2,12-dimethyl-3,7,11,17-tetraazabicyclo

[11.3.1]heptadeca-1 (17),2,11,13,15-pentaene; 2,10- dimethyl-3,6,9,12-tetraazabicyclo[9.3.1]pentadeca-1 (15)-2,10,12,15-pentaene; N-phosphonomethyliminodiacetic acid and 4,4'-dimethyl-2,2'-bipyridine.

7. The method of Claim 2 wherein said metal complex is selected from the group of complexes formed by reacting 2,2':6',2"-terpyridine and copper(II); 2,2'- bipyridine and copper(II); 4,4'-dimethyl-2,2'-bipyridine and copper(II); 7-(N-methyl)-2.,12-dimethyl-3,7,11,17- tetraazabicyclo[11.3.1]heptadeca-1 (17) ,2,11,13,15- pentaene and zinc(II).; 2,12-dimethyl-3,7,11,17- tetraazabicyclo[11.3.1]heptadeca-1 (17),2,11,13,15- pentaene and zinc (II); and 2,10-dimethyl-3,6,9,12- tetraazabicyclo[9.3.1]pentadeca-1 (15) 2 , 10, 12 , 15- pentaene and copper(II); said complexes may have ancillary ligands selected from the group consisting of chloride, hydroxide, water, bromide, iodide,

perchlorate, nitrate, sulfate, phosphines, phosphites, and other mono- and bidentate ligands.

8. A compound comprising a metal complex effective for hydrolyzing RNA covalently linked at any location where chemical derivatization is possible to a nucleoside, nucleotide or oligodeoxynucleotide.

9. A compound of Claim 8 which exhibits

hydrolysis of RNA as shown by Applicants' HPLC Assay wherein said metal complex is a nucleoside or

nucleotide.

10. A compound of Claim 8 which exhibits sequence-directed hydrolysis of RNA wherein said metal complex is linked to an oligodeoxynucleotide.

11. The compound of Claim 8 wherein said metal complex is selected from the group of complexes formed by reacting 2,2':6',2"-terpyridine and copper(II); 2,2'-bipyridine and copper(II); 4,4'-dimethyl-2,2'-bipyridine and copper(II); 7-(N-methyl)-2,12-dimethyl-3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1 (17),2,11,13,15-pentaene and zinc(II); 2,12-dimethyl-3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1 (17),2,11,13,15-pentaene and zinc (II); and 2,10-dimethyl-3,6,9,12-tetraazabicyclo[9.3.1]pentadeca-1 (15)-2,10,12,15-pentaene and copper(II); said complexes may have

ancillary ligands selected from the group consisting of chloride, hydroxide, water, bromide, iodide,

perchlorate, nitrate, sulfate, phosphines, phosphites and other mono- and bidentates.

12. A compound of Claim 8 wherein said metal complex is linked off the C-5 position of uracil in a 2'-deoxy-uridine nucleoside or nucleotide; the C-4 or C-5 position of cytosine in a 2'-deoxy-cytidine nucleoside or nucleotide; the N-6 position of adenine in a 2'-deoxy-adenosine nucleoside or nucleotide or the N-2 or 0-6 position of guanine in a 2'-deoxy-guanosine

nucleoside or nucleotide.

13. The compound of Claim 12 wherein said metal complex is selected from the group of complexes formed by reacting 2,2':6',2"-terpyridine and copper(II); 2,2'-bipyridine and copper(II); 4,4'-dimethyl-2,2'-bipyridine and copper(II); 7-(N-methyl)-2,12-dimethyl-3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1 (17) ,2,11,13,15-pentaene and zinc(II); 2,12-dimethyl-3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1 (17) ,2,11,13,15-pentaene and zinc (II); and 2,10-dimethyl-3,6,9,12-tetraazabicyclo[9.3.1]pentadeca-1 (15)-2,10,12,15-pentaene and copper(II); said complexes may have ancillary ligands selected from the group consisting of chloride, hydroxide, water, bromide, iodide,

perchlorate, nitrate, sulfate, phosphines, phosphites and other mono- and bidentate ligands.

14. The compound of Claim 8 wherein the metal in said metal complex is selected from the group consisting of copper, zinc and cobalt.

15. The compound of Claim 8 wherein the ligand in said metal complex is selected from the group consisting of 2,2'-bipyridine and substituted 2,2 '-bipyridines.

16. The compound of Claim 8 wherein the ligand in said metal complex is selected from the group consisting of 2,2':6',2"-terpyridine and substituted

2,2':6',2"-terpyridines.

17. The complex of 5-[3-[[2-[[4-[4'-methyl[2,2'- bipyridin]-4-yl]-l-oxobutyl]-amino]ethyl]amino]-3- oxopropyl]-2'-deoxy-uridine and copper(II).

18. The complex of 3'-[4-[4'-methyl(2,2'- bipyridin]-4-yl]butyl-phosphate]-2'-deoxy-thymidine ammonium salt and copper(II).

19. The complex of 5'-[4-[4'-methyl(2,2'- bipyridin]-4-yl]buty1-phosphate]-2'-deoxy-thymidine triethylammonium salt and copper(II).

20. The method of covalently linking a metal complex effective for RNA hydrolysis to a nucleoside, nucleotide or oligodeoxynucleotide comprising reacting said nucleoside, nucleotide or oligodeoxynucleotide and metal complex under conditions to covalently link said metal complex to said nucleoside, nucleotide or

oligodeoxynucleotide at any location where chemical derivatization is possible.

21. The method of Claim 20 comprising reacting said nucleoside, nucleotide or oligodeoxynucleotide and an organic ligand, when complexed with a metal ion is effective in the hydrolysis of RNA, to covalently link said organic ligand to said nucleoside, nucleotide or oligodeoxynucleotide and, then, reacting the resulting compound with a metal ion effective in the hydrolysis of RNA to attach said metal ion to said organic ligand.

22. The method of Claim 20 wherein said metal ion is first reacted with said ligand to form a complex which is then reacted with said nucleoside, nucleotide or oligodeoxynucleotide to covalently link said complex at any location where chemical derivatization is

possible.

23. In a process for the hydrolysis of RNA under physiologically relevant conditions the improvement which comprises contacting said RNA with a metal complex covalently linked to an oligodeoxynucleotide to provide sequence-directed hydrolysis.

24. The process of Claim 23 wherein said metal complex exhibits hydrolysis of RNA as shown by

Applicants' HPLC Assay.

25. The process of Claim 23 wherein said metal complex is attached to said oligodeoxynucleotide at any location where chemical derivatization is possible.

26. The process of Claim 23 wherein said metal is selected from the group consisting of copper, zinc, cobalt, nickel, palladium, lead, iridium, manganese, iron, molybdenum, vanadium, ruthenium, bismuth,

magnesium, uranium, rhodium and the Lanthanide metals.

27. The process of Claim 23 wherein said metal is selected from the group consisting of copper, zinc and cobalt.

28. The process of Claim 23 wherein the ligand of said metal complex is selected from the group of compounds consisting of 2,2':6', 2"-terpyridine; 2,2'-bipyridine; 7-(N-methyl)-2,12-dimethyl-3,7,11,17- tetraazabicyclo[11.3.1]heptadeca-1 (17),2,11,13,15-pentaene; 2,12-dimethyl-3,7,11,17-tetraazabicyclo

[11.3.1]heptadeca-1 (17) ,2,11,13,15-pentaene; 2,10-dimethyl-3,6,9, 12-tetraazabicyclo[9.3.1]pentadeca-1 (15)2, 10, 12,15-pentaene; N-phosphonomethyliminodiacetic acid and 4,4'-dimethyl-2,2'-bipyridine.

29. The method of Claim 23 wherein said metal complex is selected from the group of complexes formed by reacting 2,2' :6' ,2"-terpyridine and copper(II); 2,2'-bipyridine and copper(II); 7-(N-methyl)-2, 12-dimethyl-3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1

(17),2,11,13,15-pentaene and zinc(II); 2,12-dimethyl-3,7,11,17-tetraazabicyclo[11.3.1]]heptadeca-1

(17),2,11,13,15-pentaene and zinc(II); and 2,10-dimethyl-3,6,9,12-tetraazabicyclo[9.3.1]pentadeca-1 (15)2,10,12,15-pentaene and copper(II); said complexes may have ancillary ligands selected from the group consisting of chloride, hydroxide, water, bromide, iodide, perchlorate, nitrate, sulfate, phosphines, phosphites and other mono- and bidentate ligands.

30. The method of cleaving RNA with a compound selected from the group consisting of nucleosides, nucleotides and oligodeoxynucleotides having attached thereto two or more imidazole groups.

31. The method of Claim 30 wherein said imidazole groups are attached to said compound at any location where chemical derivatization is possible as long as the essential properties of the imidazoles remain intact, so that they may function as either acids, bases or both, in either the Lewis or Br∅nsted definitions of the terms.

32. The method of cleaving RNA with a

combination of two compounds selected from the group consisting of nucleosides, nucleotides and

oligodeoxynucleotides each having one or more imidazole groups attached thereto.

33. The method of Claim 32 wherein said imidazole groups are attached to said compounds at any location where chemical derivatization is possible as long as the essential properties of the imidazoles remain intact, so that they may function as either acids, bases or both, in either the Lewis or Brønsted definitions of the terms.

34. The method of cleaving RNA with a compound selected from the group consisting of nucleosides, nucleotides and oligodeoxynucleotides having attached thereto at least one imidazole group in the presence of a solution containing at least one imidazole group.

35. The method of Claim 32 wherein said

imidazole groups are attached to said compound at any location where chemical derivatization is possible as long as the essential properties of the imidazoles remain intact, so that they may function as either acids, bases or both, in either the Lewis or Brønsted definitions of the terms.

36. A compound comprising two or more imidazole groups effective for cleaving RNA covalently linked to a nucleoside, nucleotide or oligodeoxynucleotide at any location where chemical derivatization is possible as long as the essential properties of the imidazoles remain intact, so that they may function as either acids, bases or both, in either the Lewis or Brønsted definitions of the terms.

37. A compound of Claim 36 which exhibits sequence-directed cleavage of RNA wherein said imidazole groups are linked to an oligodeoxynucleotide.

38. A compound of Claim 36 wherein said imidazole groups are juxtaposed in an appropriate manner to enhance cleavage of RNA.

39. The compound of 5-[3-[[2-[[2-[[2-amino]-1-oxo-3-[1H-imidazol-4-yl]propyl]amino]-1-oxo-3-[1Himidazol-4-yl]propyl]amino]ethyl]amino]-3-oxopropyl]-2'-deoxyuridine.

40. A combination of compounds comprising one or more imidazole groups effective for cleaving RNA

covalently linked to two or more nucleosides,

nucleotides or oligodeoxynucleotides at any location where chemical derivatization is possible as long as the essential properties of the imidazoles remain intact, so that they may function as either acids, bases or both, in either the Lewis or Brønsted definitions of the terms.

41. The combination of compounds of Claim 40 wherein said imidazole groups are juxtaposed in an appropriate manner to enhance cleavage of RNA.

42. The method of covalently linking two or more imidazole groups effective for RNA cleavage to a

nucleoside, nucleotide or oligodeoxynucleotide

comprising reacting said nucleoside, nucleotide or oligodeoxynucleotide and imidazole groups under

conditions to covalently link said imidazole groups to said nucleoside, nucleotide or oligodeoxynucleotide at any location where chemical derivatization is possible as long as the reactivity of the imidazole is not prevented from further chemical reaction.

43. In a process for the cleavage of RNA under physiologically relevant conditions the improvement which comprises contacting said RNA with a compound selected from the group comprising two or more imidazole groups covalently linked to an oligodeoxynucleotide or two or more oligodeoxynucleotides having one or more imidazole groups covalently linked thereto to provide sequence-directed cleavage.

44. In a process for the cleavage of RNA under physiologically relevant conditions the improvement which comprises contacting said RNA with a compound selected from the group comprising one or more imidazole groups covalently linked to an oligodeoxynucleotide in the presence of a solution containing an imidazole group.

45. The process of Claim 43 wherein said

imidazole groups are attached to said oligodeoxynucleotide at any location where chemical derivatization is possible so long as the essential properties of the imidazoles remain intact, so that they may function as either acids, bases or both, in either the Lewis or Brønsted definitions of the terms.