The Metabolic Functions of Vitamin B12

RAPID progress in any area of scientific inquiry does not ordinarily occur until the problems needing solution have been formulated in terms that elicit respect for their complexities. Usually, this is made possible by a small number of key contributions. The history of our understanding of vitamin B12 is a procession of such turning points. The most recent is undoubtedly the discovery of a coenzyme form of vitamin B12 by Barker and his associates1 in 1958. This brilliant contribution initiated a series of biochemical studies that have, at last, provided meaningful clues to the role of vitamin B . . .