Purification and some physicochemical properties of staphylococcal enterotoxin E.

Enterotoxin E produced by Stu~hyZococcus aureus strain FRI (Food Research Institute)-326 was purified by cation exchange chromatography on carboxymethylcellulose, gel tiltration through superfine Sephadex G-75, and gel filtration in 6 M urea with superfine Sephadex G-75. The purified toxin appears to be nearly homogeneous by paper, starch gel, and polyacrylamide gel electrophoresis and double gel diffusion tests. It is a simple, colorless, antigenic protein. Its molecular weight was determined to be 29,600 f 500 by sucrose density gradient centrifugation, molecular sieve chromatography on Sephadex G-100, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Its toxicity and reaction with its specific antibody are destroyed by extreme acidic (pH 2) and basic (pH 12) conditions. Urea-treated enterotoxin E retains its toxic activity and reaction with its speciiic antibody after removal of the denaturing agent. The enterotoxin consists of 259 amino acid residues and contains no free sulfhydryl groups. End group analysis showed serine to be the NHa-terminal amino acid and threonine to be the COOH-terminal amino acid.