Liou Jau-Cheng, Cheng Yun-Ching, Kang Kai-Hsiang, Chu Yuan-Ping, Yang Chen-Chung, Chang Long-Sen
Department of Biological Sciences, National Sun Yat-Sen University, Kaohsiung 804, Taiwan, ROC.
Toxicon. 2004 Mar 1;43(3):341-6. doi: 10.1016/j.toxicon.2004.01.007.
In the present study, Xenopus nerve-muscle cultures were used to explore the functional roles of A chain (a phospholipase A(2) subunit) and B chain (a non-phospholipase A(2) subunit) of Bungarus multicinctus beta-bungarotoxin. It was found that beta-bungarotoxin induced an increment of the frequency of spontaneous synaptic currents (SSCs) in the nerve-muscle cultures. Modification of beta-bungarotoxin with pyridoxal-5'-phosphate or substitution of Ca(2+) with Ba(2+) in buffer abolished the phospholipase A(2) activity of beta-bungarotoxin and the facilitatory phase of SSC as well. Antibodies that were directed specifically against A chain or B chain effectively inhibited phospholipase A(2) activity, and as a consequence the SSC frequency was not greatly different from the control rate. These results suggest that both A and B chains are indispensable parts of beta-bungarotoxin for inducing the facilitation of SSC frequency with Xenopus nerve-muscle cultures.
在本研究中，非洲爪蟾神经肌肉培养物被用于探究多环眼镜蛇β-银环蛇毒素的A链（一种磷脂酶A2亚基）和B链（一种非磷脂酶A2亚基）的功能作用。研究发现，β-银环蛇毒素可使神经肌肉培养物中自发突触电流（SSCs）的频率增加。用磷酸吡哆醛修饰β-银环蛇毒素或在缓冲液中用Ba2+替代Ca2+，均可消除β-银环蛇毒素的磷脂酶A2活性以及SSC的促进阶段。特异性针对A链或B链的抗体可有效抑制磷脂酶A2活性，结果SSC频率与对照率无显著差异。这些结果表明，对于在非洲爪蟾神经肌肉培养物中诱导SSC频率的促进作用而言，A链和B链都是β-银环蛇毒素不可或缺的部分。
