Regulation of Staphylococcus protease using complement, interferon and immunoglobulin as substrates

The effects of various agents on the cleavage of serum albumin, interferon, immunoglobulin and complement component C1q by the extracellular protease from Staphylococcus aureus were analysed by SDS-polyacrylamide gel electrophoresis. Arachidonic acid moderately stimulated the proteolysis of serum albumin, interferon and complement component. Phosphatidic acid effectively enhanced the proteolysis of serum albumin and IgG, whereas it inhibited the cleavage of IgM. The proteolysis of IgG was appreciably enhanced by sphingosine. In contrast, phosphatidyl choline and phosphatidyl glycerol were shown to have an inhibitory effect on the proteolysis of IgG and IgM. Phosphatidyl serine, phosphatidyl inositol and phosphatidyl ethanolamine also inhibited the proteolysis of IgG. The failure of any of these agents to exert a persistent effect on the cleavage of all substrates, revealed the complexity of the interactions among the agent, the substrate and the protease.