K. Ichinose, M. Kodera, F. J. Leeper and A. R. Battersby
"Proof that the Biosynthesis of Vitamin B12 Involves a Reduction Step in an Anaerobic as well as an Aerobic Organism"
J. Chem. Soc., Chem. Commun.,1993, 515-517. Full Text
Labelling experiments with 2H and 3H prove that as cobyrinic acid is biosynthesised by the anaerobic bacterium Propionibacterium shermanii, its H-19 is derived from HR (and not HS) at C-4 of a reduced nicotinamide cofactor, so demonstrating that the biosynthetic pathway involves a reduction step.
Department of Chemistry
University of Cambridge