Venera G D, Testai F D, Peña C, Lacorazza H D, Biscoglio De Jiménez Bonino M J
Instituto de Quimica y Fisicoquímica Biológicas (UBA-CONICET), Facultad de Farmacia y Bioquimica, Buenos Aires, Argentina.
Neurochem Int. 1997 Jul;31(1):151-7. doi: 10.1016/s0197-0186(96)00063-0.
Peptides corresponding to the sequence alpha 124-147 of the Torpedo californica and Homo sapiens nicotinic cholinergic receptors were synthesized. The His residue at position 134 was ethoxyformylated or substituted by Ala. Effects of such modifications were studied by: (a) a toxin blot assay and (b) a competition assay between each peptide and the Discopyge Ischudii receptor for 125I alpha-bungarotoxin, in solution. Apparent Kd values were 0.1 and 0.8 microM for Torpedo californica and Homo sapiens native peptides, respectively, and no binding was observed when the His residue was modified or substituted by Ala. ic50 values for the Torpedo californica and Homo sapiens fragments were 1.0 and 0.8 microM, respectively, and no significant displacement occurred when His 134 was ethoxyformylated or substituted by Ala. Hydroxylamine treatment restored 80-100% of their binding ability. Results strongly support the involvement of His 134 in the binding of alpha-bungarotoxin either to the Torpedo californica or the Homo sapiens receptor.
合成了与加州电鳐和人类烟碱型胆碱能受体序列α124 - 147相对应的肽段。134位的组氨酸残基被乙氧基甲酰化或被丙氨酸取代。通过以下方法研究了这些修饰的效果：(a)毒素印迹分析；(b)在溶液中，每种肽段与伊氏盘魟受体竞争125Iα-银环蛇毒素的竞争分析。加州电鳐和人类天然肽段的表观解离常数（Kd）值分别为0.1和0.8微摩尔，当组氨酸残基被修饰或被丙氨酸取代时未观察到结合。加州电鳐和人类片段的半数抑制浓度（ic50）值分别为1.0和0.8微摩尔，当134位组氨酸被乙氧基甲酰化或被丙氨酸取代时未发生明显的置换。羟胺处理恢复了它们80 - 100%的结合能力。结果有力地支持了134位组氨酸参与α-银环蛇毒素与加州电鳐或人类受体结合的观点。
