The biochemistry and enzymology of amino acid dehydrogenases

This review is an exhaustive description of the biochemistry and enzymology of all 17 known NAD(P)⁺-amino acid dehydrogenases. These enzymes catalyze the oxidative deamination of an amino acid to its keto acid and ammonia, with the concomitant reduction of either NAD⁺or NADP⁺. These enzymes have many important applications in industrial and medical settings and have been the object of prodigious enzymological research. This article describes all that is known about the poorly characterized members of the family and contains detailed information on the better characterized enzymes, including valine, phenylalanine, leucine, alanine, and glutamate dehydrogenases. The latter three enzymes have been the subject of extensive enzymological experimentation, and, consequently, their chemical mechanisms are discussed. The three-dimensional structure of the Clostridium symbiosumglutamate dehydrogenase has been determined recently and remains the only structure known of any amino acid dehydrogenase. The three-dimensional structure and its implications to the chemical mechanisms and rate-limiting steps of the amino acid dehydrogenase family are discussed.