Effects of ganglioside GM1 on the thermotropic behavior of cholera toxin B subunit.
Effects of ganglioside GM1 on the thermotropic behavior of cholera toxin B subunit.
复制标题
神经节苷脂 GM1 对霍乱毒素 B 亚基热致行为的影响。
DOI：
10.1007/bf00230165
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发表时间：
1984
影响因子：
4.3
通讯作者：
Schafer,DE
中科院分区：
文献类型：
--
作者：
Dalziel,AW;Lipka,G;Chowdhry,BZ;Sturtevant,JM;Schafer,DE
霍乱肠毒素的 B 亚基或结合亚基在完整毒素中形成五聚环结构，当该亚基与 A 亚基分离时也是如此。在神经节苷脂 GM1（其天然“受体”）存在和不存在的情况下，通过差示扫描量热法检查 B 亚基环的热变性。在不存在神经节苷脂的情况下，观察到不可逆吸热，最大过量表观热容 Cmax 在 74.6°C。当以增加的量添加神经节苷脂时，在较高温度下观察到多重转变，最显着的 Cmax 为 90.8°C。在高神经节苷脂浓度下，没有观察到 74.6°C 转变。除了热力学结果之外，还提出了 GM1 和 B 亚基五聚体相互作用的模型。该模型的推导与量热结果无关（但与此类数据一致），并且基于对 GM1 胶束-B 亚基五聚体几何形状的考虑。
The B, or binding, subunit of cholera enterotoxin forms a pentameric ring structure in the intact toxin, and also when the subunit is isolated from the A subunit. The thermal denaturation of the B subunit ring was examined by differential scanning calorimetry in the presence and absence of ganglioside GM1, its natural ‘receptor’. In the absence of ganglioside an irreversible endotherm was observed with maximal excess apparent heat capacity, Cmax, at 74.6° C. When the ganglioside was added in increasing amounts, multiple transitions were observed at higher temperatures, the most prominent having a Cmaxat 90.8° C. At high ganglioside concentrations, the 74.6° C transition was not observed. In addition to the thermodynamic results a model is proposed for the interaction of GM1and B subunit pentamer. This model is derived independently of the calorimetric results (but is consistent with such data) and is based upon considerations of the geometry of the GM1micelle-B subunit pentamer.