Design and Synthesis of a Peptide Having Chymotrypsin-Like Esterase Activity

A peptide having enzyme-like catalytic activity has been designed and synthesized. Computer modeling was used to design a bundle of four short parallel amphipathic helical peptides bearing the serine protease catalytic site residues serine, histidine, and aspartic acid at the amino end of the bundle in the same spatial arrangement as in chymotrypsin (ChTr). The necessary "oxyanion hole" and substrate binding pocket for acetyltyrosine ethyl ester, a classical ChTr substrate, were included in the design. The four chains were linked covalently at their carboxyl ends. The peptide has affinity for ChTr ester substrates similar to that of ChTr and hydrolyzes them at rates approximately 0.01 that of ChTr; total turnovers greater than 100 have been observed. The peptide is inhibited by ChTr specific inhibitors and is inactive toward benzoyl arginine ethyl ester, a trypsin substrate. The peptide is inactivated by heating above 60 degrees C, but recovers full catalytic activity upon cooling and lyophilization from acetic acid.