THE ACTION OF STREPTOLYSIN S ON MOUSE- LIVER MITOCHONDRIA

Summary We studied the action of streptolysin S on the respiration of mouse-liver mitochondria. Preparations of RNA-streptolysin S (RNA-SLS) impaired the succinic- and cytochrome-oxidase activity of these organelles. The ability to damage mitochondria could not be separated from the haemolytic activity of the toxin. The presence of exogenous cytochrome C prevented impairment of these enzymatic activities by RNA-SLS and reversed the observable effects of the toxin on them. Thus it appeared that streptolysin S causes dislocation of the electron-transport between cytochrome C and oxygen. The ability of group-A streptococci to impair mitochondrial respiration may be of importance in the mechanism of pathogenicity.