Madsen G L, Knoop F C
Infect Immun. 1980 Jun;28(3):1051-3. doi: 10.1128/iai.28.3.1051-1053.1980.
Concentrated cell-free filtrates, prepared from a human strain of enterotoxigenic Escherichia coli, were subjected to isoelectric focusing, molecular sieve chromatography, and polyacrylamide disc gel electrophoresis. Isoelectric focusing in a pH 3 to 5 gradient resulted in two biologically active peaks, I and II, that electrofocused at pI 1.5 and 3.8, respectively. Molecular sieve chromatography of the major enterotoxic peak (II) at pH 3.8 indicated a molecular weight of 2,500. Polyacrylamide disc gel electrophoresis of ST revealed a single protein band containing enterotoxic activity.
从一株产肠毒素的人源大肠杆菌制备的浓缩无细胞滤液，进行了等电聚焦、分子筛层析和聚丙烯酰胺圆盘凝胶电泳。在pH 3至5梯度下进行等电聚焦，产生了两个生物活性峰，峰I和峰II，它们分别在pI 1.5和3.8处电聚焦。在pH 3.8对主要肠毒素峰（峰II）进行分子筛层析，表明其分子量为2500。对耐热肠毒素（ST）进行聚丙烯酰胺圆盘凝胶电泳，显示出一条含有肠毒素活性的单一蛋白带。
