[An enzymic assay for the determination of vitamin B12 (author's transl)].

A procedure which extends the very sensitive propanediol-dehydratase reaction for 5'-deoxy-5'-adenosylcobalamine determination to cyanocobalamine and hydroxocobalamine is described. In this procedure, the cobalamines are adenosylated by vitamin B12 coenzyme synthetase and the resulting 5'-deoxy-5'-adenosylcobalamine can be determined by the propanediol-dehydratase reaction. Aldehyde, the product of the latter, can be registered by the alcohol dehydrogenase reaction.