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首页> 外文期刊>Infection and immunity >An intact interchain disulfide bond is required for the neurotoxicity of tetanus toxin.
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An intact interchain disulfide bond is required for the neurotoxicity of tetanus toxin.

机译：破伤风毒素的神经毒性需要完整的链间二硫键。

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摘要

Tetanus toxin is composed of a heavy chain (100 kDa) and a light chain (50 kDa) held together by a single interchain disulfide bridge. An additional intrachain disulfide is present in the carboxy-terminal part of the heavy chain. Reduction of the two disulfide bonds in tetanus toxin with both chemical and proteinaceous reducing agents was studied. Dithiothreitol and 2-mercaptoethanol cleaved both the inter- and intrachain disulfide bridges of the toxin, while glutathione and cysteine were ineffective. Specific reduction of the single interchain disulfide link was achieved with the thioredoxin-thioredoxin reductase system, thus indicating that this bond is exposed at the protein surface. Also, dead or permeabilized cells were able to reduce the toxin. Such reduced toxin bound to neuronal membranes as well as the native toxin but was not neurotoxic. These findings open the possibility that reduction by cytoplasmic agents released by dead cells contributes to detoxification of tetanus toxin. Moreover, together with the notion that the light chain is the active form of the toxin in the cytoplasm, these results suggest that the interchain disulfide bond of tetanus toxin plays a role in nerve cell penetration.
机译：破伤风毒素由一条重链（100 kDa）和一条轻链（50 kDa）通过一条链间二硫键连接在一起。另外的链内二硫键存在于重链的羧基末端部分。研究了用化学还原剂和蛋白质还原剂还原破伤风毒素中的两个二硫键。二硫苏糖醇和2-巯基乙醇裂解了毒素的链间和链内二硫键，而谷胱甘肽和半胱氨酸无效。通过硫氧还蛋白-硫氧还蛋白还原酶系统实现了单个链间二硫键的特异性还原，因此表明该键暴露于蛋白质表面。同样，死细胞或透化细胞能够减少毒素。这种减少的毒素与神经元膜以及天然毒素结合，但是没有神经毒性。这些发现打开了由死细胞释放的细胞质剂减少有助于破伤风毒素解毒的可能性。此外，连同轻链是毒素在细胞质中的活性形式的观点一起，这些结果表明破伤风毒素的链间二硫键在神经细胞渗透中起作用。

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