Inactivation of Staphylocoagulase by Trypsin and Pepsin

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Abstract
Cultures of a coagulase-positive strain of Staphylococcus aureus grown for 7 days in tryptic digest medium were used as a source of coagulase. After incubation, 0.5% phenol was added, centrifuged, and the clear supernates used. Coagulase activity was titrated by a serial dilution method. Commercial trypsin and U.S.P. pepsin were used. Five ml. of the supernate plus 20 mg. of the enzyme were incubated at 37[degree] C for 2-2.5 hrs., with shaking. Controls were run using heat-inactivated enzyme and also with no enzyme present. Before titration of coagulase, tryptic action was checked by heating for 5 min. at 80[degree] C; peptic action, by adjusting the reaction to pH 8. The prepns. were cleared by centrifugation, and the coagulase titer detd. The activity of the enzyme prepns. was checked by measuring the protein N. There was complete destruction of coagulase activity in all expts. with active enzymes. There was a one-dilution decrease in coagulase activity in 1 control, otherwise no decrease in the controls.

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