Tsuji T, Taga S, Honda T, Takeda Y, Miwatani T
Infect Immun. 1982 Nov;38(2):444-8. doi: 10.1128/iai.38.2.444-448.1982.
The heat-labile enterotoxins produced by human enterotoxigenic Escherichia coli (LTh) and porcine enterotoxigenic E. coli (LTp) were purified to homogeneity, and their molecular properties were compared with those of purified cholera enterotoxin (CT). On polyacrylamide gel disk electrophoresis without sodium dodecyl sulfate, LTh, LTp, and CT differed in mobility, suggesting differences in their ionic charges. The pI values of LTh, LTp, and CT were 7.50, 8.10, and 6.80, respectively. On sodium dodecyl sulfate-polyacrylamide gel slab electrophoresis, the B subunit and A1 and A2 fragments of LTh, LTp, and CT differed in mobility, suggesting that they differed in molecular size. Their molecular sizes seemed to decrease in the following order: B subunit, LTh greater than LTp congruent to CT; A1 fragment, LTp greater than LTh congruent to CT; A2 fragment, LTh congruent to CT greater than LTp. Amino acid compositions of LTh, LTp, and CT were also compared.
人产肠毒素大肠杆菌产生的热不稳定肠毒素（LTh）和猪产肠毒素大肠杆菌产生的热不稳定肠毒素（LTp）被纯化至均一，并且将它们的分子特性与纯化的霍乱肠毒素（CT）的分子特性进行了比较。在不含十二烷基硫酸钠的聚丙烯酰胺凝胶圆盘电泳中，LTh、LTp和CT在迁移率上有所不同，表明它们的离子电荷存在差异。LTh、LTp和CT的pI值分别为7.50、8.10和6.80。在十二烷基硫酸钠-聚丙烯酰胺凝胶平板电泳中，LTh、LTp和CT的B亚基以及A1和A2片段在迁移率上有所不同，表明它们在分子大小上存在差异。它们的分子大小似乎按以下顺序减小：B亚基，LTh大于LTp等同于CT；A1片段，LTp大于LTh等同于CT；A2片段，LTh等同于CT大于LTp。还比较了LTh、LTp和CT的氨基酸组成。
