Protein‐chemical analysis of pertussis toxin reveals homology between the subunits S2 and S3, between S1 and the A chains of enterotoxins of Vibrio cholerae and Escherichia coli and identifies S2 as the haptoglobin‐binding subunit

摘要

>The purified toxin of Bordetella pertussis was dissociated in 5 M urea in the presence of immobilized haptoglobin. The toxin was dissociated in free S₁, free S₅ and the free complexes S₂-S₄ and S₃-S₄, with S₂-S₄ as the only haptoglobin-binding moiety, identifying S₂ as the haptoglobin-binding protein. Partial NH₂-terminal amino acid sequences were obtained from the dissimilar toxin subunits, after separation by SDS-polyacrylamide gel electrophoresis followed by electroblotting onto polybrene-coated glass-fiber sheets. The sequences reveal extensive homology of the N-terminal portions of the constitutive subunits S₂ and S₃ and between S₁ and the enterotoxin A chains of Vibrio cholerae and Escherichia coli.