IN VITRO AGGREGATION OF PLATELETS INDUCED BY ^|^alpha;-TOXIN (PHOSPHOLIPASE C) OF CLOSTRIDIUM PERFRINGENS

Abstract

Highly purified α-toxin (phospholipase C) of Clostridium per-fringens prepared by affinity chromatography on agarose-linked egg-yolk lipoprotein induced the in vitro aggregation of platelets of an irreversible type. The aggregation started after a time lag, the length of which depended on the concentration of the toxin; the reciprocal of the time lag was found to be directly proportional to the toxin concentration. Using this assay method, we demonstrated that the platelet-aggregating activity of α-toxin reached minimum at around 70 C but heating at higher temperatures inactivated it to a lesser extent; the same anomaly in heat inactivation was observed with phospholipase C activity possessed by the toxin. By subjecting purified α-toxin to isoelectric focusing, four molecular forms were isolated, all of which were associated with both the platelet-aggregating and phospholipase C activities. From all these results we concluded that the entity responsible for the platelet-aggregating activity is identical with α-toxin (phospholipase C) .