RT Journal Article SR Electronic(1) A1 Smyth, C. J.YR 1975 T1 The Identification and Purification of Multiple Forms of θ-Haemolysin (θ-Toxin) of Clostridium perfringens Type A JF Microbiology, VO 87 IS 2 SP 219 OP 238 DO https://doi.org/10.1099/00221287-87-2-219 PB Microbiology Society, SN 1465-2080, AB The θ-haemolysin of Clostridium perfringens was purified from culture supernatant fluids of type A strains fractional ammonium sulphate precipitation and isoelectric focusing in narrow pH 5 to 8 gradients. Four components detected on electrofocusing were designated θ 1 (p1 6·8 to 6·9),θ 2 (p1 6·5 to 6·6),θ 3 (p1 6·1 to 6·3) and θ 4 (p1 5·7 to 5·9). Specific activities ranged from 0·4×106 to 1·2×106 haemolytic units/mg protein and 2950 to 3600 LD50/mg protein. Each haemolytic component was activated cysteine hydrochloride, and inactivated cholesterol, addition of sheep erythrocyte ghosts and heating at 60 ° C for 10 min; mouse erythrocytes were more resistant than sheep erythrocytes to haemolysis. A reaction of identity was obtained between components in gel diffusion. Sodium dodecyl sulphate polyacrylamide disc gel electrophoresis gave molecular weights in the range 59000 to 62000 for each component. A similar value was obtained for θ 1 on density gradient ultracentrifugation. Although the multiple forms were free of 11 factors present in culture supernatants, crossed immunoelectrophoresis and disc gel electrophoresis revealed minor contaminants. These studies reveal that θ-haemolysin has physical properties in common with other oxygen-labile haemolysins., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-87-2-219