Isoelectric analysis of cytolytic bacterial proteins.

In this note, we describe the application of isoelectric focusing to the characterization of two cytolytic proteins, the a-toxin or phospholipase C of Clostridium perfringens (clostridial PLC) and cereolysin. We used a 110-ml electrolysis column (LKB Instruments, Rockville, Md.), the design of which was given by 0. Vesterberg et al. (Biochem. Biophys. Acta 133:435, 1967), who also summarized the theoretical and practical filtrate of C. perfringens Type A, kindly supplied by R. 0. Thomson (Weilcome Research Laboratories, Beckenham, Kent, England), and with the same conditions (without a pH gradient) used by Bangham and Dawson, but substituting sucrose for glycerol, we obtained (Fig. 1) a single peak of phospholipase activity, as measured by the capacity of fractions to cause turbidity in diluted egg yolk.