The clotting activity of Staphylococcus aureus strain 104 was purified 46,000-fold, but absolute purity was not achieved. Carbohydrate content of the purified material was not more than 5%. Elution of clotting activity from denaturing and nondenaturing polyacrylamide gels revealed the presence of four distinct molecular forms. Molecular weights of the forms were approximately 31,500, 34,800, 44,800, and 56,800 as determined by gel filtration in 8 M urea, by sodium dodecyl sulfate-urea polyacrylamide gel electrophoresis, and by calculation with determined values for the Stokes radius and sedimentation coefficient. Molecular weights determined on sodium dodecyl sulfate-urea gels were found to decrease as the gel concentration increased, suggesting that the amount of sodium dodecyl sulfate bound was less than normal. Estimated frictional ratios for the forms showed that they differ in shape from one another and that they are all highly asymmetrical. Each of the forms had an isoelectric point between pH 5.44 and 5.47 when focused in 6% polyacrylamide gels for 9 h; however, prolonged focusing altered the isoelectric point of the forms to within the range of pH 4.35 to 4.65. The multiple clotting forms were not artifacts of the purification procedure and did not appear to be products of the proteolytic degradation of a larger protein.

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AND MORRIS TAGER. Enzymatic activities associated with clotting of fibrinogen by staphylocoagulase and coagulase-reacting factor and their inhibition by diisopropylfluorophosphate. J. Bacteriol. 83:975-980. 1962.-The chemical mechanism of fibrinogen clotting by staphylocoagulase and its plasma factor (CRF) involves a preliminary stage of proteolysis, analogous to that found in thrombin-catalyzed fibrinogen clotting. Coagulase-CRF also exhibits N-a-toluene-p-sulfonyl-L-arginine methyl ester

Fibrinogen clotting and fibrino-peptide formation by staphylocoagulase and the coagulase-reacting factor. J. Bacteriol. 85:628-635. 1963.-The mechanism of fibrinogen clotting by staphylocoagulase and the coagulase-reacting factor (CRF) was studied from the standpoint of the products of the reaction, and compared with thrombin clotting of fibrinogen. Both clotting principles effect clotting with the release of nonprotein nitrogenous material, which can be resolved into three peptides by Dowex-50 chromatography. On the basis of the sedimentation constants, electrophoretic mobilities, and end-group analyses of these peptides, it appears that the products of fibrinogen clotting by coagulase-CRF and by thrombin are similar.

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