van Heyningen S
Biochem J. 1977 Dec 15;168(3):457-63. doi: 10.1042/bj1680457.
Reaction of cholera toxin with NN'-bis(carboximidomethyl)tartaramide dimethyl ester produced several cross-linked species that had subunit B (which binds to the cell surface) and peptides A1 (which activates adenylate cyclase) and A2 all covalently joined together. This cross-linded material had activity with pigeon erythrocytes that was comparable in all respects with that of native toxin. It activated the adenylate cyclase of whole cells, showing a characteristic lag phase, and this activation was increased if the cells had been preincubated with ganglioside GM1, but abolished if the protein had been preincubated with the ganglioside. It activated the enzyme in lysed cells more strongly and without the lag phase. These results show that the toxin is active even when peptide A1 cannot be released from the rest of the molecule.
霍乱毒素与NN'-双（羧基亚氨甲基）酒石酰胺二甲酯反应产生了几种交联产物，这些产物中，亚基B（与细胞表面结合）、肽A1（激活腺苷酸环化酶）和A2都通过共价键连接在一起。这种交联物质对鸽红细胞具有活性，在各方面都与天然毒素相当。它能激活全细胞的腺苷酸环化酶，呈现出典型的延迟期，并且如果细胞预先与神经节苷脂GM1孵育，这种激活作用会增强，但如果该蛋白质预先与神经节苷脂孵育，激活作用则会消失。它对裂解细胞中的酶激活作用更强，且没有延迟期。这些结果表明，即使肽A1无法从分子的其余部分释放出来，毒素仍然具有活性。
