Biosynthesis of vitamin B12: evidence from double-labelling studies (13CD3) for intact incorporation of seven methyl groups

Abstract

The deuterium noise-decoupled ¹³C n.m.r. spectrum of dicyanocobalamin (5) biosynthesised from [methyl-¹³CD₃]methionine shows intact incorporation of seven methyl groups into the macrocycle of vitamin B₁₂ without exchange of D with H of the medium.