STUDIES ON CHYMOTRYPSIN-LIKE CATALYSIS BY SYNTHETIC PEPTIDES

The synthetic peptide Chymohelizyme-1 (CHZ-1) exhibits esterase activi ty against carbobenzoxytyrosine p-nitrophenyl ester (ZTONP), carbobenz oxyalanine p-nitrophenyl ester (ZAONP), and t-butyloxycarbonyltyrosine p-nitrophenyl ester (BocTONP). However, earlier reports of catalytic activity against less labile esters and amides have proven to be incor rect. The major reason for the errors appears to have been the omissio n of certain controls in the previous work. Although the catalytic tri ad does not appear to be functioning as designed, the catalytic activi ty of CHZ-1 does depend on the integrity of its primary structure. The pH dependence of hydrolysis of ZTONP points to general-base catalysis , whereas a preference for hydrophobic substrates suggest that the str ucture of CHZ-1 is performing some other role in assisting catalysis.