Reductive Amination - Biochemistry

Biochemistry

A step in the biosynthesis of many α-amino acids is the reductive amination of an α-ketoacid, usually by a transaminase enzyme. The process is catalyzed by pyridoxamine phosphate, which is converted into pyridoxal phosphate after the reaction. The initial step entails formation of an imine, but the hydride equivalents are supplied by a reduced pyridine to give an aldimine, which hydrolyzes to the amine. The sequence from keto-acid to amino acid can be summarized as follows:

HO₂CC(O)R → HO₂CC(=NCH₂-X)R → HO₂CCH(N=CH-X)R → HO₂CCH(NH₂)R.