INHIBTION OF RESTRICTION ENDONUCLEASE CLEAVAGE BY TEIPLEXFORMATION WITH OLIGO-2'-O-METHYL-RIBONUCLEOTIDES CONTAINING 8-OXO-2'-O-METHYLADENOSINE IN PLACE OF CYTIDINE

摘要

The ability of homopyrimidine oligoribonucleotides and oligo-2,-O-methyl-ribonucleotides containing 8-oxo-adenosine (AOH) and 8-oxo-2'-O-methyl-(AmOH) adenosine to form stable,triple-helical structures with sequences containing the recognition site for the class II-S restriction enzyme,Ksp632-1,was studied as a function of pH. The AOH-and AmoH-substituted oligoribonucleotides and oligo-2'-O-methyl-ribonucleotides were shown to bind within the physiological pH range in a pH-independent fashion,without a compromise in specificity.The substitutions of three cytidine residues with AOH showed higher endonuclease inhibition than the substitution of either one or two cytidine residues with AOH.In particular,the oligo-2'-O-methyl-ribonucleotide with only one cytidine substituted with AmOH showed higher endonuclease inhibition.Increased resistance to nucleases in observed with the introduction of 2'-O-methylnucleosides.This stabilization should help us to design much more efficient third strand homopyrimidine oligomer and antisense nucleic acid,which can be used as tools in cellular biolgy and anti-viral therapy.