Biochemical studies on the relationship between Clostridium perfringens alpha toxin and CTP-binding protein in rabbit erythrocytes.

我们用中性氨基酸(丙氨酸、亮氨酸和甘氨酸)取代了产气荚膜梭菌α毒素中的所有9个组氨酸残基，并研究了其生物活性与毒素中组氨酸残基或锌离子的关系。结果表明，毒素中的组氨酸-11残基被认为是毒素蛋白中必不可少的组成部分，组氨酸-68、-126和136残基结合了可交换和不稳定的二价金属，这对膜和底物的结合是重要的，组氨酸-148残基与一种锌金属紧密结合。

We replaced all nine histidine residues in Clostridium perfringens alpha toxin with neutral amino acids (alanine, leucine and glycine) by site-direct mutagenesis and investigated the relationship between the biological activities and histidine residues or zinc ion in the toxin.The results suggested that the histidine-11 residue in the toxin is regarded as an essential and integral part of the toxin protein, that the histidine-68, -126 and 136 residues bind an exchangeable and labile divalent metal which is important for binding to membranes and substrates and that the histidine-148 residue tightly binds one zinc metal which is essential for the active or catalytic site of alpha toxin.