Re-investigation of the effect of 2′-O-methylation on pyrimidine nucleosides in terms of the pseudo-rotational analysis of the furanose ring

Abstract

The scope of the pseudorotational analysis of the ribose ring has been investigated in terms of the limitations of the analysis imposed by the use of one Karplus relation for each molecular fragment and by the errors in the determination of the observed coupling constants. The method is illustrated by a re-investigation of the conformational properties of the pyrimidine nucleosides and the effect of 2′-O-methylation on the ribose ring. It is found that temperature changes and O-methylation do not alter the conformational parameters of the furanose ring but that they alter the equilibrium compositions.