Preparation of Azacrown-Functionalized 2‘-O-Methyl Oligoribonucleotides, Potential Artificial RNases

Abstract

An improved synthesis for 3-(3-aminopropyl)- and 3-(3-mercaptopropyl)-1,5,9-triazacyclododecane has been developed and alternative methods for their conjugation to oligonucleotides have been described. Accordingly, the 3-aminopropyl azacrown and its N-(3-aminopropanoyl)-3-aminopropyl analogue have been tethered to the 3'-terminus of a 2'-O-methyloligoribonucleotide by aminolytic cleavage of the thioester linker utilized for the chain assembly. Studies on a monomeric model compound verify that the reaction proceeds solely by the attack of the primary amino group. 5'-Conjugation has been achieved by introducing a 2-benzylthio-2-oxoethyl group to the 5'-terminus as a phosphoramidite reagent and cleaving the thioester bond with the 3-aminopropyl azacrown. For intrachain conjugation, a phosphoramidite reagent derived from 1-deoxy-1-(2-benzylthio-2-oxoethyl)-beta-d-erythro-pentofuranose has been inserted in a desired position within the chain and subjected to on-support aminolysis with the 3-aminopropyl azacrown or its N-(3-aminopropanoyl)-3-aminopropyl and N-(6-aminohexanoyl)-3-aminopropyl analogues. The 3-mercaptopropyl-derivatized azacrown has been tetherd by a disulfide bond to a 3'-(3-mercaptoalkyl)phosphate-tailed oligonucleotide. The 3'- and intrachain-tethered conjugates have been shown to cleave as their Zn(II) chelate complementary oligoribonucleotide sequences.

Synthesis of Aminoglycoside Conjugates of 2′-O-Methyl Oligoribonucleotides

“…1 (33). Compound 32 was synthesized as described earlier (36,37). tert-Butyldimethylsilyl chloride (1.43 g, 9.5 mmol) was added to a mixture of 32 (2.4 g, 4.7 mmol) and a catalytic amount of imidazole in pyridine (20 mL).…”

Enhanced RNA cleavage within bulge-loops by an artificial ribonuclease

“…Indeed, it was shown that cleavage of RNA by lanthanide (La 3+ and Eu 3+ ) complex conjugated to antisense oligonucleotide (17) or by transition metal complexes conjugated to 2′- O -methyl oligoribonucleotides (18) occurs more efficiently when the target sequence is located within a bulge loop. Thus, oligonucleotide binding, yielding highly reactive bulge loops, can thus be considered as an approach to induction of unique reactive sites in RNA, which can be selectively cleaved by small catalytic molecules.…”

Ribonucleases as antiviral agents

“…The effect of other agents is selectively targeted against various stages of viral infection development and the life cycle of the virus, i.e., adsorption, penetra tion, synthesis of virus components, and the exit of daughter virions form cell. Agents that act upon virus genome are of particular interest; they include anti sense oligonucleotides [56], ribozymes [57], and RNases discussed here. These agents suppress virus production, but they are probably able to destroy latent virus infection.…”