某些疾病是由感染菌分泌的酶作用引起的。白喉毒素就是这类酶的一种,它具有很强的毒性,只要一个分子进入胞浆,靶细胞就会死亡。它和其它许多毒素一样,有A、B二个亚单位组成。B亚单位是与真核细胞受体结合的成分;A亚单位是具有 Some diseases are caused by the action of enzymes secreted by the infected bacteria. Diphtheria toxin is a kind of enzyme, it has a strong toxicity, as long as a molecule into the cytoplasm, the target cell will die. Like many other toxins, it consists of two subunits, A and B. The B subunit is a component that binds to the eukaryotic receptor; the A subunit is