Ho C L, Wu S H, Chen C J
Biochim Biophys Acta. 1983 Jan 25;755(2):210-6.
Carbamidomethylation of the reduced Cys29-Cys33 bridge of alpha-bungarotoxin (Bungarus multicinctus postsynaptic neurotoxin) did not alter the LD50 or irreversibility of the toxin, while carboxymethylated alpha-bungarotoxin was less potent and its neuromuscular blocking action in mouse diaphragm was reversible. The circular dichroic spectra of both modified toxins were similar but slightly different from that of native toxin. Neuromuscular transmission in the chick biventer cervicis nerve-muscle preparation could be blocked by the carboxymethylated toxin, and reactivated by washing, whereas the response of the muscle to extrinsic acetylcholine could also be blocked but was hardly restored by washing. These results suggest that carboxymethylated toxin can differentiate between junctional and extrajunctional acetylcholine receptors in chick skeletal muscle.
对α-银环蛇毒素（多环眼镜蛇突触后神经毒素）还原后的Cys29 - Cys33桥进行氨甲酰甲基化，并未改变毒素的半数致死量（LD50）或不可逆性，而羧甲基化的α-银环蛇毒素效力较低，其在小鼠膈神经上的神经肌肉阻断作用是可逆的。两种修饰毒素的圆二色光谱相似，但与天然毒素的光谱略有不同。羧甲基化毒素可阻断鸡双腹神经-肌肉标本中的神经肌肉传递，通过冲洗可使其恢复，而肌肉对外源性乙酰胆碱的反应也可被阻断，但冲洗后几乎无法恢复。这些结果表明，羧甲基化毒素能够区分鸡骨骼肌中接头处和接头外的乙酰胆碱受体。
