抄録
Nα Benzyloxycarbonyl p-guanidine-L-phenylalanine β-naphthylamide (Z-GPA-βNA) was synthesized and the susceptibility of this compound to trypsin and related enzymes was compared with that of Nα benzyloxycarbonyl-L-arginine β-naphthylamide (Z-Arg-βNA). Both Z-GPA-βNA and Z-Arg-βNA were rapidly and almost completely hydrolyzed by trypsin and pronase. Z-Arg-βNA was hydrolyzed slowly by thrombin, while Z-GPA-βNA was not susceptible to this enzyme at all. The rate of hydrolysis of Z-GPA-βNA by papain was slower than that of Z-Arg-βNA. Neither β-naphthylamide substrate was hydrolyzed by α-chymotrypsin. The specificity constant (kcat/Km) for the hydrolysis of Z-GPA-βNA by trypsin was somewhat larger than that for the hydrolysis of Z-Arg-βNA. Contributions of the benzene ring in the side chain of Z-GPA-βNA to good binding of this substrate to the specificity site of this enzyme and to the poor fit of the scissile bond in the substrate molecule to the active serine residue are presumed from comparison of the individual kinetic parameters (Km and kcat) for the two β-naphthylamide substrates. Z-GPA-βNA was ascertained to be a useful substrate in the study of the binding and catalytic specificities of various trypsin-like enzymes.
