CONFORMATIONAL STUDIES ON DIRIBONUCLEOSIDE MONOPHOSPHATE ANALOGS CONTAINING A NONISOSTERIC, ISOPOLAR, PHOSPHONATE-BASED INTERNUCLEOTIDE LINKAGE

Two types of (2'-5') and (3'-5') isomers of phosphonate analogs of dir ibonucleotides derived from 2'-, 3'- or 5'-O-phosphonomethyl ribonucle osides, that differ in the position of methylene group in the phosphon ate internucleotide linkage, have been studied in aqueous solution by NMR techniques in order to compare their basic structural features wit h those of the natural (3'-5') diribonucleotides. Despite the addition al methylene group in the ribose-phosphate backbone, dinucleoside phos phonates are structurally and conformationally very similar to their n atural counterparts.