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金环蛇神经毒素与乙酰胆碱受体结合的特点

徐科, 陈丽筠, 江明恃

中国科学院上海生理研究所. 上海

摘要

进一步纯化了前一工作中从广西省产金环蛇(Bungarus fasciatus)蛇毒分离的突触后毒素Ⅰ和Ⅱ。以超饱和剂量的毒素Ⅰ或Ⅱ先与从电鳐(Narcine maculata)电器官得到的乙酰胆碱受体(AChR)保温10min 或 1h,再加入~(125)Ⅰ-标记α-银环蛇毒素或~(125)Ⅰ-标记眼镜蛇毒素,继续保温10min 或 lh,由测定与 AChR 结合的放射性强度得知,如以未经毒素Ⅰ或Ⅱ预饱和的放射性强度为100%,则经与其一预饱和者的约为30%,即毒素Ⅰ或Ⅱ只竞争地阻遏了α-银环蛇毒素或眼镜蛇毒素与 AChR 结合能力的2/3左右。文中讨论了存在两种类型 AChR 的可能性。

关键词： 金环蛇神经毒素; α-银环蛇毒素; 眼镜蛇毒素; 乙酰胆碱受体; 眼镜蛇毒素-4B 亲和层析

A binding characteristic of neurotoxins from bungarus fasciatus venom to acetylcholine receptor

Hsu Ke, Chen Lijun, Jiang Mindshi

Shanghai Institute of Physiology, Academia Sinica. Shanghai, China

Abstract

The crude venom of Bungarus fasciatus was fractionated by ion-exchange chromatography on a CM-Sephadex C-50 column into 11 fractions. Two neurotoxic fractions obtained were further purified on CM-Cellulose C-32 and Sephadex G-50 columns. They were basic proteins and named as neurotoxin I (TI) and neurotoxin II (TH). Both of them lacked phospholipase A activity. Test of neuromuscular transmission on the chick biventer cervicis nerve-muscle preparation showed that both TI and TII belonged to the postsynaptic type. The mouse minimal lethal dose (i. p.) of TI and TII was about 200 r and 250 r per kg body weight respectively. The competitive inhibitory effects of the two neurotoxins on the binding of ~(125)I-bungarotoxin or ~(125)I-cobrotoxin to AChR were studied. After preincubation of the narcine AChR (Triton X-100 solubilized extract or the preparation further purified by affinity chromatography) with various amounts of TI or TII (for 10 minutes or 1 hour), ~(125)I-bungarotoxin or ~(125)I-cobrotoxin were added and the residual binding of the latter to AChR were determined. The results showed that even with excessive amounts of TI or TII, the total binding of u-bungarotoxin or cobrotoxin to AChR was only competitively blocked about 2/3. The possibility of two kinds of AChR existing was discussed.

Key words: Bungarus fasciatus neurotoxin;Alpha-bungarotoxin;Cobrotoxin;Acety1choline receptor;Cobrotosin-4 B affinity chromatography

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引用本文：

徐科, 陈丽筠, 江明恃. 金环蛇神经毒素与乙酰胆碱受体结合的特点[J]. 生理学报 1985; 37 (2): .

Hsu Ke, Chen Lijun, Jiang Mindshi. A binding characteristic of neurotoxins from bungarus fasciatus venom to acetylcholine receptor. Acta Physiol Sin 1985; 37 (2): (in Chinese with English abstract).