Protease Inhibitors Produced by Streptomyces libani

Abstract

Chymotrypsin and trypsin inhibitors were produced simultaneously in the culture broth of Streptomvices libani S-35. These inhibitors were purified and obtained as white amorphous powders. The properties of the chymotrypsin inhibitor were similar to those of known chymo-statins except that it was positive for Sakaguchi reaction. The presence of arginine residue was further confirmed by ¹³C-NMR study and, therefore, the inhibitor was presumed to be a new Sakaguchi-positive chymostatin in which the capreomycidine of chymostatin B was replaced by arginine. The properties of the trypsin inhibitor were the same as those of antipain. The Sakaguchi-positive chymostatin and the antipain were the same in amino acid sequence except that the former had phenylalaninal and the later had argininal at the C-terminal.