PLP-dependent Enzymes: a Powerful Tool for Metabolic Synthesis of Non-canonical Amino Acids

An Overview on PLP-dependent Enzymes Pyridoxal 5’-phosphate (PLP), the biologically active of vitamin B6, was first identified in the mid-forties as the cofactor for the transamination reaction. Since then, PLP-dependent enzymes have been the focus of extensive biochemical research. The interest aroused by these enzymes is due to their unrivalled catalytic versatility and their widespread involvement in cellular metabolism. As a matter of fact, PLP acts as cofactor in more than 160 different enzymes classified by the Enzyme Commission, representing 4% of all known cellular catalytic activities [1]. PLP-dependent enzymes serve vital roles in all living organisms and catalyze a number of diverse chemical reactions, such as transamination, decarboxylation, racemization, carbon-carbon bond cleavage and formation. PLP-dependent activities are involved in essential biosynthetic pathways including glucose and lipid metabolism, 27