Saiani L, Kageyama H, Conti-Tronconi B M, Guidotti A
Mol Pharmacol. 1984 Mar;25(2):327-34.
In primary cultures of bovine chromaffin cells, commercially available preparations of alpha-bungarotoxin inhibit the acetylcholine (ACh)- or nicotine-evoked release of endogenous catecholamines. The potency of different lots of alpha-bungarotoxin is not related to the alpha-bungarotoxin peptide content but to that of another peptide (termed P-4 bungarotoxin) present as an impurity in the alpha-bungarotoxin preparations. P-4 Bungarotoxin was isolated and purified to homogeneity by high-pressure liquid chromatography (HPLC). Homogeneity was established by a variety of means, including polyacrylamide gel electrophoresis, HPLC, end carboxy group analysis and NH2-terminal amino acid sequence. Purified P-4 bungarotoxin contains approximately 121 amino acid residues, and it is different in its amino composition, molecular weight, and amino acid sequence from alpha-bungarotoxin and beta-bungarotoxin. P-4 Bungarotoxin (IC50 congruent to 1 nM) blocked the ACh-induced release of endogenous catecholamines but failed to block the KCl-induced catecholamine release. Although P-4 bungarotoxin is endowed with phospholipase A2 activity, its effect on ACh-evoked catecholamine release persists when the phospholipase activity is blocked (99.9%) by treatment of the toxin with p-bromophenacyl bromide. P-4 Bungarotoxin may represent a useful tool with which to study nicotinic receptor function in sympathetic and central nervous system neurons.
在牛嗜铬细胞的原代培养物中，市售的α-银环蛇毒素制剂可抑制乙酰胆碱（ACh）或尼古丁诱发的内源性儿茶酚胺释放。不同批次的α-银环蛇毒素的效力与其α-银环蛇毒素肽含量无关，而是与作为α-银环蛇毒素制剂中的杂质存在的另一种肽（称为P-4银环蛇毒素）的含量有关。通过高压液相色谱（HPLC）将P-4银环蛇毒素分离并纯化至同质。通过多种方法确定其同质性，包括聚丙烯酰胺凝胶电泳、HPLC、末端羧基分析和NH2末端氨基酸序列。纯化的P-4银环蛇毒素含有约121个氨基酸残基，其氨基酸组成、分子量和氨基酸序列与α-银环蛇毒素和β-银环蛇毒素不同。P-4银环蛇毒素（IC50约为1 nM）阻断了ACh诱导的内源性儿茶酚胺释放，但未能阻断KCl诱导的儿茶酚胺释放。尽管P-4银环蛇毒素具有磷脂酶A2活性，但在用对溴苯甲酰溴处理毒素使磷脂酶活性被阻断（99.9%）时，其对ACh诱发的儿茶酚胺释放的作用仍然存在。P-4银环蛇毒素可能是研究交感神经系统和中枢神经系统神经元中烟碱受体功能的有用工具。
