Purification of free staphylococcal coagulase

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Abstract
The conditions under which free coagulase of high specific activity is liberated in the culture fluid were investigated. Optimum conditions were obtained when a heavy inoculum of a fully grown digest-broth culture was seeded into a casein-hydrolysate medium and shaken for 1 hour 20 minutes at 37[degree]. The enzyme was isolated in an electrophoretically homogeneous form by adsorption on to cadmium sulfate, followed by fractional precipitation with ammonium sulfate. On electrophoresis the purified enzyme had an isoelectric point of about pH 5.3. Ultracentrifuging a slightly impure preparation showed a minimum mean molecular weight of approximately 44,000. The material was extremely toxic when injected intravenously into rabbits, and a concentration of 75 [mu][mu]g/ml clotted human plasma in 24 hours.