A thiol protease of peritoneal macrophages in the guinea pig

Summary Proteolytic enzymes of the guinea pig peritoneal exudate macrophages were investigated using synthetic fluorogenic peptide substrates. Among several enzymes, t-butyloxycarbonyl-phenylalanyl-seryl-arginine 4-methylcoumaryl-7-amide cleaving enzymes had the highest activity, and the activity in exudate macrophages was about 3 times tronger than that in resident thiol-blocking reagents, suggesting a thiol protease.We thank Dr Yoshiaki Motozato, Kumamoto University, for kind donation of Cellulofine GC-700 and valuable discussions. This work is supported in part by the Grant-in-Aid for Scientific Research from the Ministry of Education, Science and Culture of Japan.