title: Purification and some physicochemical properties of staphylococcal enterotoxin D.
abstract: A method was developed for the isolation of staphylococcal enterotoxin D in highly purified form from cultures of Staphylococcus aureus strain 1151m. The method involves removal of the toxin from the culture supernatant fluid with the ion-exchange resin CG-50 followed by chromatography on carboxymethylcellulose (twice) and by gel filtration on Sephadex G-75 (twice). The purified toxin is homogeneous by polyacrylamide gel and sodium dodecyl sulfate-polyacrylamide gel electrophoresis and double gel diffusion tests. It is a simple, colorless, antigenic protein with an isoelectric point of 7.4 as determined by isoelectric focusing. Its molecular weight was determined to be 27 300 +/- 700 by molecular sieve chromatography on Sephadex G-100 and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Its serological activity is stable over a wide range of pH values (1.2--10.7). The enterotoxin consists of 236 amino acid residues and contains no free sulfhydryl groups. End-group analysis showed serine to be the NH2-terminal amino acid and lysine to be the COOH-terminal amino acid.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D004768:Enterotoxins / Q000302:isolation & purification / Q000633:toxicity; D000882:Haplorhini; D008253:Macaca mulatta; D008970:Molecular Weight; D013211:Staphylococcus aureus / Q000032:analysis*
chemical_list: D000596:Amino Acids; D004768:Enterotoxins; C019368:enterotoxin D, Staphylococcal