PubMed1977
380 (80%) of 475 Staphylococcus aureus cultures isolated from humans, cattle and dogs were proteolytically active either on casein or gelatin or both (table 1). Protease-activity could also be demonstrated in experimental body-cavities of rabbits (fig. 1). The enzyme-activity was estimated with azocasein. Protease from S. aureus, M 135 precipitated from the culture supernatant with ammonium sulfate at 65% saturation (table 2). It was purified by 2 filtrations on Ultrogel AcA 44 (fig. 2,3) and subsequent isoelectric focusing between pH 3.5-7.0 (fig. 4). The purified protease yielded only 1 line in the SDS-polyacrylamidegel-electrophoresis, in the gelatin-polyacrylamidegel-electrophoresis and in the double immuno-diffusion test (fig. 5). Its isoelectric point was at pH 4.6, and its highest proteolytic activity between pH 7.5-8.3. The molecular weight was estimated by SDS-polyacrylamidegel-electrophoresis to be near 29.000. The protease-activity was completely inhibited in the presence of EDTA, partially inhibited by Cu2+ and Zn2+ and increased by Mn2+ (table 3).