STAPHYLOCOCCAL SPHINGOMYELINASE (β‐HEMOLYSIN) *

Staphylococcal sphingomyelinase ( sphingomyelin choline phosphohydrolase) activity was discovered by Doery and co1leagues.l Subsequent work in the same laboratory led to the conclusion that staphylococcal P-hemolysin and sphingomyelinase (and lysophosphatidase) were activities of one protein.? This belief was amply confirmed by the findings of other investigator^.^-^ We undertook to purify staphylococcal p-toxin (the term is here used synonymously with staphylococcal &hemolysin and staphylococcal sphingomyelinase) because (1) the enzyme may prove useful in the study of cell membranes by virtue of its substrate specificity, (2) we wished to investigate the dramatic increases in hemolytic activity described by others during purification, and ( 3 ) it has as yet been only partially characterized. Although purification of this cytolytic toxin has been described repeatedly,'! 5 , i-12 our results are presented because they differ in several respects from those already reported. The effect of the purified enzyme on erythrocyte ghosts was studied for the first time.