Purification and Some Chemical and Physical Properties of Staphylococcal Enterotoxin A
FORT DETRICK FREDERICK MD
Pagination or Media Count:
Enterotoxin A from a selected high toxin producing strain 15-25 microgramsml in deep culture of Staphylococcus aureus, designated 13N-2909, has been obtained in highly purified form as indicated by sedimentation velocity, sedimentation equilibrium, disc electrophoresis, and several immunological procedures. Purification was accomplished by the following STEPS 1 removal of the toxin from culture diluted five times with water, and adjusted to pH 5.6 with CG-50 carboxylic acid resin 2 chromatography on carboxymethylcellulose 3 chromatography on hydroxlapatite and 4 filtration on Sephadex G-75. Two major and two minor components were found by isoelectric focusing. The enterotoxin has a molecular weight of 27,800 as determined by sedimentation equilibrium. A value of 27,500 was obtained from polyacrylamide gel electrophoresis in the presence of denaturant. The molecule is a single polypeptide chain with one disulfide bridge and no free sulfhydryl groups. Serine was identified as the C-terminal residue but no free N terminal was found. A complete amino acid analysis is reported.