Purification of heat-labile enterotoxin from Escherichia coli O78:H11 by affinity chromatography with antserum to Vibrio cholerae toxin.

Concentrated culture filtrate of Escherichia coli O78:H11, strain H10407, was applied to an affinity column prepared with IgG antibodies to the toxin of Vibrio cholerae. Elution of the retained material with 3 M KCNS yielded a nonenterotoxic protein that precipitated with antiserum to V. cholerae toxin and had three major protein components on sodium dodecyl sulfate gels. After treatment with 2-mercaptoethanol, two protein components were observed. Elution of the affinity column with 5 M guanidine yielded an enterotoxic protein that precipitated with antiserum to V. cholerae toxin. After treatment with 2-mercaptoethanol, only one protein component, with mobility identical to that of the slower component of the eluate (treated with 3 M KCNS and 2-mercaptoethanol), was observed.