Cathepsins B, H and L in Peritoneal Macrophages and Hepatopancreas of Carp Cyprinus carpio

Abstract

Monolayer macrophages were prepared from carp peritoneal exudate cells by the intraperitoneal induction of sodium caseinate, and three distinct cathepsins, cathepsins B, H, and L, were isolated from the cell extract of peritoneal macrophages. The optimum hydrolysis pHs and temperatures of cathepsins B, H, and L were determined to be pH 6.0 and 40°C, pH 6.5–7.0 and 45°C, and pH 6.5 and 50°C, respectively. While their stable pH ranges varied widely, all cathepsins retained considerable thermostability below 45°C. They were significantly inactivated by E-64, DTNB, antipain, leupeptin, CdCl2, CuCl2, HgCl2, and Zn(CH3COO)2, but markedly activated by cysteine and 2-mercaptoethanol. Various enzymatic characteristics of macrophage cathepsins B, H, and L correspond with their respective hepatopancreas counterparts, indicating that these three cathepsins in both carp tissues are fundamentally identical.