Conformation of 2′-0-methyl cytidine, a modified furanose component of ribonucleic acids

Abstract

The crystal structure of an orthorhombic form of 2′-0-methyl cytidine was determined from three dimensional X-ray diffraction data. The two molecules in each asymmetric unit have C2- endo C3- exo puckered furanose rings. This differs from the C3- endo puckering observed for cytidine (1) and it may have some relevance to the kinks that appear at the two 2′-0-methylated nucleotides in the anticodon phosphate ester backbone of the phe tRNA structure (2). This work and other studies (3,4) show that the presence of a 2′-0-methyl group does not prevent the furanose moiety from adopting its most commonly observed configurations. 2′-0-methyl nucleotides make up a small percentage of the residues in HnRNA, rRNA, tRNA and mRNA and therefore their conformational nuances are of interest.