ABSTRACT
Crude and purified preparations of commercial alpha toxin from Clostridium peifringens were heated in physiological saline and in fractions separated from proteose peptone (Difco, 0120). Heating temperatures ranged from 55-95 C for 6-18 min. Alpha toxin remained active at temperatures ⩽ 85 C when heated in the presence of a fraction of proteose peptone having a MW ⩾ 50,000. At 95 C, some destruction was observed with a D-value of 444 min. In saline or a proteose peptone fraction having a MW < 50,000, heat inactivation of alpha toxin occurred at 65 C. Gel filtration revealed that heat protection was associated with complex formation of the alpha toxin with proteose peptone. Alpha toxin heat-treated in saline was reactivated when proteose peptone was added after heat treatment and the toxin was subsequently incubated in hemolysin indicator plates at 37 C for 24 h. Reactivation of alpha toxin was not observed when saline was added after the toxin was heat-treated and then incubated in hemolysin indicator plates at 37 C for up to 48 h.
