Investigations on the enzymes and toxins of staphylococci. Stimulation of coagulase biosynthesis by glucose and bicarbonate

Partial purification and characterization of the multiple molecular forms of staphylococcal clotting activity (coagulase)

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.

Continuous culture studies on the production of staphylocoagulase by Staphylococcus aureus

The production of staphylocoagulase was studied with continuous cultures of various S. aureus strains in a simple salts medium supplemented with mannitol, casein hydrolysate and three vitamins. Conditions of low oxygen availability and magnesium-limitation were required for optimal steady-state staphylocoagulase production. It was demonstrated that the specific rate of staphylocoagulase production was dependent on the growth rate. In two bovine strains, the production rate pattern was similar to that of an inducible enzyme sensitive to catabolite repression, although no specific inductor suppressor could be demonstrated. The human strain, on the other hand, produced staphylocoagulase constitutively. In all strains the specific rate of production of total extracellular protein was strictly proportional to the growth rate. The bovine strains produced 6 times more staphylocoagulase in chemostat culture as compared with batch cultures of the same organisms. It is likely that mannitol functioned as an energy source rather than as a carbon source because it was converted for a major part to acetate and for a minor part to lactate and not to new cell material. Repression and staphylocoagulase production by mannitol, acetate or lactate was not observed. The probable nature of the regulating mechanism(s) underlying staphylocoagulase production is discussed.

Release of beta-lysin from platelets by thrombin and by a factor produced in heparinized blood

Removal of calcium by either citrate, oxalate, or ethylenediaminetetraacetate inhibited coagulation of blood at an early stage and prevented the release of beta-lysin from platelets. In contrast, heparin caused platelet agglutination and stimulated beta-lysin release in vitro and in vivo. This release was calcium dependent and may have been due to a calcium-dependent reaction in the blood coagulation sequence. Thrombin which by-passed the early calcium-dependent stages of coagulation directly stimulated the release of beta-lysin from platelets. However, thrombin alone or in combination with other plasma factors was not as effective in releasing beta-lysin as the regular coagulation process. Thrombin's platelet degranulating activity correlated with its beta-lysin releasing activity. In contrast to thrombin, staphylococcal coagulase, which also by-passed the calcium-dependent stages of coagulation, coagulated citrated blood without releasing beta-lysin. The release of beta-lysin has been observed previously in the absence of blood coagulation, but this is the first observation of coagulation without beta-lysin release. It is clear that beta-lysin is released from platelets during coagulation by the direct action of thrombin and that it may be released in an earlier calcium-dependent reaction.