Coenzyme-B-12-dependent glutamate mutase

Adenosylcobalamin (coenzyme B-12)-dependent glutamate mutase catalyzes a mo st unusual carbon skeleton rearrangement involving the isomerization of L-g lutamate to L-threomethylaspartate, a reaction that is without precedent in organic chemistry. This reaction proceeds through a mechanism involving fr ee radical intermediates that are initiated by homolysis of the cobalt-carb on bond of the coenzyme. The enzyme serves as a paradigm for adenosylcobala min-dependent catalysis and, more generally, provides insights into how enz ymes generate and control reactive free radical species, This review descri bes how recent studies on the mechanism and structure of glutamate mutase h ave contributed to our understanding of adenosylcobalamin-mediated catalysi s. (C) 2000 Academic Press.