The synthesis and properties of phosphopyridoxyl amino acids

The conversion of substrate into product catalyzed by an enzyme with a prosthetic group is known to involve a number of stages during which the substrate is bound covalently with the coenzyme. For pyridoxal enzymes, and particularly for transaminases, Schiff bases formed by amino acids and pyridoxal-5-phosphate (PLP) are considered the major type of these intermediate complexes. From a purely chemical viewpoint it is evident, that besides these major forms there must also exist others, e.g., containing no double bond between coenzyme and substrate. We have recently proposed, that compounds which are structural analogues of the substrate-coenzyme complexes may be inhibitors of prosthetic group-containing enzymes, particularly, of the PLP-enzymes /1/. In the present paper we report the synthesis of previously unknown N-(pyridoxyl-5′-phosphate)-amino acids (P-Pyl-amino acids) and the results of the studies on their interaction with some transaminases whose coenzyme is PLP and whose substrates are L-amino acids.