Abstract
Staphylococcal [Staphylococcus aureus] .alpha.-toxin of MW 39,000 was degraded at an alkaline pH by staphylococcal extracellular proteases resulting in the formation of 3 relatively stable intermediates with MW 27,500, 23,500 and 12,000. The intermediate with MW 27,500, which existed in 2 charged forms, was isolated by column chromatography and found to be non-hemolytic. It could be obtained by proteolysis of .alpha.-toxin (MW 39,000) with chymotrypsin in low concentrations. This intermediate was further degraded by trypsin to the protein with MW 23,500 and 12,000.