Studies of staphylokinase.

Summary Staphylokinase in the supernatant of cultures of Staphylococcus aureus was concentrated and then purified twice successively by isoelectric focusing. The total activity of staphylokinase was increased about 100 per cent. after the first isoelectric focusing. The cause of this was investigated. It was also shown by means of this separation technique that staphylokinase is a heterogenous protein, with isoelectric points at pH 5.8 (component A), 6.2 (component B) and 6.8 (component C). The degree of purification was calculated. Some properties of the components were studied. The effects of the following metal ions: Ca++, Mg++, Mn++, Cu++, Pb++, Zn++, Ag+ and Co++; and of EDTA and cysteine, were examined. No significant differences in these respects between the three components were observed. The pH for optimal activity also seemed to be the same for the main components.