Characterization of two acid proteinases found in rabbit skin homografts

Abstract

Two types of acid proteinase activity found in rabbit skin homografts were characterized by studying the effect of temperature, pH and polyacrylamide-gel electrophoresis. Their chromatographic behavior was characterized on DEAE-cellulose, Sephadex G-75, G-100 and G-200 and their MW were estimated by gel filtration. One of the acid proteinases in the homograft resembled cathepsin D (EC 3.4.23.5) of normal skin. The other acid proteinase differed from cathepsin D with respect to heat inactivation, pH optimum and MW; it was not inactivated on heating at 60.degree. C for 60 min, its pH optimum was 2.5 and its MW measured by Sephadex G-100 chromatography was 100,000. In all these respects, the heat-stable proteinase resembles cathepsin E (EC 3.4.23.5) of rabbit polymorphonuclear leucocytes.