A comparative study of two serotypes of epidermolytic toxin from Staphylococcus aureus

Two serotypes of epidermolytic toxin were purified from culture filtrates of different strains of Staphylococcus aureus. The amino acid composition of the proteins is similar, each containing no cystine and one methionine, but type ii contains no tryptophan, whereas type i has 1 mol/mol protein. The molecular weights of type i and type ii toxins were 30,000 and 29,500, respectively, as found by SDS-polyacryamide gel electrophoresis and confirmed by studies of CNBr fragments and tryptic peptides. Dansylation gave a single different N-terminal amino acid for each toxin; the C-terminus of each is lysine. Peptide mapping of tryptic digests showed that very few peptides are common to the two amino acid sequences.