Biosynthesis of vitamin B12: the macrocycle and studies on the geminal methyl groups of ring c

Abstract

The biosynthesis of vitamin B₁₂ is studied by ¹³C-spectroscopy on the derived heptamethyl ester (4); work with amino[5-¹³C]lavulinic acid and [Me-¹³C]- methionine confirms that seven peripheral methyl groups are derived from methionine and proves that one of these is the pro-R methyl group on ring c.