Chang Long-Sen, Chu Yuan-Ping, Cheng Yun-Ching, Liou Jau-Cheng, Yang Chen-Chung
Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung 804, Taiwan, ROC.
Toxicon. 2005 Feb;45(2):179-85. doi: 10.1016/j.toxicon.2004.10.006.
Two beta-bungarotoxin isotoxins BM12 and BM13 were isolated from Bungarus multicinctus (Taiwan banded krait) venom by sequential chromatography on ion-exchange and reverse phase columns. The two toxins have the same A chain, but different B chains. Different phospholipase A2 activity and different potencies in inhibiting the spontaneous enhancement of spontaneous synaptic current frequency and muscle contraction were observed for BM12 and BM13. Nevertheless, modification of Lys-64 in the A chain of BM12 and BM13 similarly reduced in their phospholipase A2 activity and toxicity. The modified derivatives retained their affinity with Ca2+ and their conformation as deduced by CD. These results suggest that Lys-64 of the A chain is involved in the phospholipase A2 activity and in the neurotoxic effect of beta-bungarotoxin.
通过离子交换柱和反相柱的连续色谱法，从多环扁尾海蛇（台湾带纹海蛇）毒液中分离出两种β-银环蛇毒素同毒素BM12和BM13。这两种毒素具有相同的A链，但B链不同。观察到BM12和BM13具有不同的磷脂酶A2活性，以及在抑制自发突触电流频率和肌肉收缩的自发增强方面具有不同的效力。然而，BM12和BM13的A链中Lys-64的修饰同样降低了它们的磷脂酶A2活性和毒性。修饰后的衍生物保留了它们与Ca2+的亲和力以及通过圆二色性推断的构象。这些结果表明，A链的Lys-64参与了磷脂酶A2活性以及β-银环蛇毒素的神经毒性作用。
