PURIFICATION AND CHARACTERIZATION OF ENTEROTOXIC MOIETY PRESENT IN CELL-FREE CULTURE SUPERNATANT OF SALMONELLA-TYPHIMURIUM

The enterotoxic moiety present in the cell-free culture supernatants o f Salmonella typhiurium strains (p/536 and p/603) was purified to appa rent homogeneity by salt precipitation with ammonium sulphate and succ essive chromatography through Sephadex G-100 and G-200 columns. It was nondialysable, heat labile at 90 degrees C and active within pH 6-8. Its activity was completely lost on treatment with trypsin, protease a nd papain. The enterotoxin appeared to be of high molecular weight (10 0 kDa) and was highly immunogenic in rabbit. Antigenically, it was not related to cholera toxin, Shiga toxin or the heat labile enterotoxin of Escherichia coli. It did not bind to the GM, ganglioside. The enter otoxic, delayed permeability and CHO cell elongation activities were a ttributed to a single protein moiety.