The application of QAE-Sephadex for the purification of two staphylococcal enterotoxins. II. Purification of enterotoxin A.

The last three steps described in the preceding communication Robern, H., Stavric, S. and Dickie, N. (1975) Biochim. Biophys. Acta 000,000-000) were utilized successfully for the purification of enterotoxin A. The enterotoxin appeared homogeneous by gel chromatography and in the analytical ultracentrifuge but showed two bands on polyacrylamide disc electrophoresis at pH 4.5. The emetic dose, ED50, by intravenous route in cynomolgus monkeys was 0.12 mug/kg of animal weight. After treatment with beta-mercaptoethanol, urea and sodium dodecylsulfate enterotoxin A formed one band corresponding to a molecular weight of about 27700 on sodium dodecylsulfate gel electrophoresis. Molecular-weight estimation by gel filtration gave a value of 26500. The amino acid composition data indicate that enterotoxin A consists of 241 amino acid residues.