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金环蛇毒膜活性多肽B在脂双层中形成离子通道的作用

施玉樑, 王文萍, 张辉, 徐科

中国科学院上海生理研究所 上海 200031

摘要

利用由卵磷脂和胆固醇（分别为20和5mg/ml）的正癸烷溶液形成的平板脂双层,观察了由金环蛇毒纯化的膜活性多肽B（BMAP B）形成通道的作用。实验结果表明,在膜两侧有一定电位差或盐浓度梯度的条件下,BMAP B参入脂双层形成离子通道,在电压箝位下可记录出不同电导的单位电导涨落,随着更多通道的形成,脂双层稳态膜电阻明显降低;通过在不对称盐溶液中测定平衡电位,确定BMAP B通道的阴阳离子选择性不强,PK/PCl≈1.4;和在生物膜的作用一样,二价金属离子Ba2+,Ca2+抑制BMAP B通道的活动。这些结果为金环蛇毒膜活性多肽在生物膜的去极化作用提供了解释。

关键词： 金环蛇毒; 膜活性多肽; 平板脂双层; 离子通道; 单位电导涨落; 二价金属离子

Channel-forming activity at planar lipid bilayer of the membrane active polyptide B form venom of Bungarus Fasciatus

SHI Yu-Liang, WANG Wen-Ping, Zhang Hui, Xu Ke

Shanghai Institute of physiology, Academia Sinica,Shanghai 200031

Abstract

Using planar lipid bilayer formed by lecithin and cholesterol （20 and 5 mg/mlrespectively in N-decane） the channel-forming activity of the membrane activepolypeptidc B（BMAP B） from the venom of Bungarus fasciatus was investigated.Under the existance of a voltage or a salt concentration gradient between two sidesof the bilayer, unit conductance fluctuation and a decrease in steady state resistanceaccompanying BMAP B incorporation and channel formation were observed. Bymeasuring the reversal potential in an asymmetric solution, the selectiviy of theBMAP B-channel was estimated having a value of PK/PCl=1.4. Divalent cations,such as Ba2+, Ca2+ inhibited the channel activity as they did in biomembranes.These data might provide an explanation for the depolarizing effect of the mem-brane active polypeptide on the native membranes.

Key words: bungraus venom;membr aneactive polypeptide;planar lipid bilayer;Ion channel;unit conductance fluctuation;divalent cations

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引用本文：

施玉樑, 王文萍, 张辉, 徐科. 金环蛇毒膜活性多肽B在脂双层中形成离子通道的作用[J]. 生理学报 1992; 44 (6): 533-540.

SHI Yu-Liang, WANG Wen-Ping, Zhang Hui, Xu Ke. Channel-forming activity at planar lipid bilayer of the membrane active polyptide B form venom of Bungarus Fasciatus. Acta Physiol Sin 1992; 44 (6): 533-540 (in Chinese with English abstract).