Reactions of the cyano and alkyl cobalamins

Abstract

Previous investigations have shown that the action of chloramine T or brominewater solution at pH 4 on cyanocobalamin first causes cyclization of the acetamide side chain of ring B to form cobalamin lactone and that the further action of chloramine T causes substitution of chlorine into the chromophore yielded the chlorocobalamin lactone (Bonnett et al. 1957). The chlorination of cobalamin coenzyme, methyl cobalamin or cobalamin-sulphonate took a different course (Wagner & Renz 1963; Wagner & Bernhauer 1964; Dolphin, Johnson & Rodrigo 1964). The first equivalent of chloramine T causes in this product substitution of chlorine into the chromophore without cyclization and only the further action of chloramine T leads to the formation of the corresponding monochlorolactones.