Enzyme-Catalyzed Irreversible Formation of Peptides Containing D-Amino Acids

Article abstract of DOI:10.1021/jo00364a021

Procedures have been developed for the preparation of dipeptides Z-L-Tyr-D-X and Z-L-Phe-D-X using Z-L-Tyr-OMe (or Z-L-Phe-OMe) and D-amino acid esters or amides (D-X) as substrates and soluble or immobilized α-chymotrypsin as a catalyst.The formation of each of these peptides in miscible or immiscible organic solvent-water systems in a kinetically controlled approach is virtually irreversible with no side reactions or racemization.Kinetic studies indicate that D-amino acid esters are about 100 times that of water and 10percent that of L-amino acid esters as a nucleophile in deacylation reactions.The effects of pH, organic solvents, temperature, and substrate and enzyme concentrations on the yield and the stability of the enzyme in syntheses have been studied and the results compared with those in the enzyme-catalyzed formation of L-L-dipeptides.