Purification and characterization of a wall protein antigen from Clostridium botulinum type A.

A wall surface protein, designated antigen S, was extracted from Clostridium botulinum type A strain 190L with 0.1% Brij 58-2 M LiCl and purified sequentially by acetone pecipitation, ion-exchange chromatography, hydroxyapatite chromatography, chromatofocusing, and gel filtration. Crossed immunoelectrophoresis of the purified antigen S preparation against homologous multispecific antiserum to whole cells revealed only a single precipitin line. Antigen S had an apparent molecular weight of about 195,000, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The antigen was composed predominantly of acidic amino acid residues, and the isoelectric point was estimated to be at pH 4.75. Tryptic digestion of antigen S destroyed antigenic activity and produced one major polypeptide fragment with a molecular weight of about 44,000. Indirect immunoferritin labeling showed that antigen S was located on the outer layer of the cell wall.