Biosynthesis of vitamin B12: origin of the hydrogen atoms at C-18 and C-19
Abstract
When cobyrinic acid is biosynthesised from uro'gen-III in deuterium oxide, deuterium is inserted at both C-18 and C-19 as shown by 13C n.m.r.; this is a further result in keeping with a biosynthetic sequence for the corrin ring of vitamin B12 involving no external redox reagents.