The sporulation-specific enterotoxin of Clostridium perfringens type A, which is the toxin active in human food poisoning, has been purified from extracts of sporulating cells. Highly purified enterotoxin was obtained by treatment of crude cell extract with ribonuclease for 30 min, followed by sequential chromatography on Sephadex G-100, Cellex T cellulose, and hydroxylapatite. Recovery was 65 to 75% of the initial activity. Enterotoxin purity was > 99% as indicated by sedimentation velocity, sedimentation equilibrium, disc electrophoresis, and serological methods. Purified enterotoxin focused at pH 4.3 during isoelectric focusing. Molecular weights of 34,000 and 35,000 were obtained by Sephadex G-100 chromatography and sedimentation equilibrium, respectively. An S20,w of 3.08 was obtained for the purified enterotoxin. The enterotoxin precipitated heavily at its isoelectric point and at concentrations greater than 4 mg/ml.
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