放射性标记的α-银环蛇毒素衍生物：与烟碱型乙酰胆碱受体的动力学相互作用。
Radiolabeled alpha-bungarotoxin derivatives: kinetic interaction with nicotinic acetylcholine receptors.
作者信息
Lukas R J, Morimoto H, Hanley M R, Bennett E L
出版信息
Biochemistry. 1981 Dec 22;20(26):7373-8. doi: 10.1021/bi00529a008.
The binding interactions of purified tritiated [3H]-alpha-Bgt and monoiodinated and diiodinated derivatives of alpha-bungarotoxin with membrane-bound nicotinic acetylcholine receptors (nAChR) from Torpedo californica electroplax and rat brain have been characterized by several kinetic and equilibrium techniques. By all criteria, [3H]-alpha-Bgt and 125I-labeled monoiodinated alpha-Bgt ([125I]-alpha-Bgt) exhibited comparable specificities and affinities for nAChR. In contrast, affinity of nAChR for 125I-labeled diiodinated alpha- Bgt ([125I2]-alpha-Bgt) was reduced, and [125I2]-alpha-Bgt-nAChR complexes showed anomalous biphasic dissociation kinetics. [125I]-alpha-Bgt and [125I2]-alpha-Bgt binding was inhibited most potently by native alpha-Bgt as opposed to iodinated toxins. [3H]- alpha-Bgt was the radiotoxin most resistant to inhibitory influences. The use of well-characterized, chemically modified alpha -Bgt derivatives may identify ligand binding microheterogeneities and tissue-specific receptor subclasses.
利用多种动力学和平衡技术，对纯化的氚化[3H]-α-银环蛇毒素（α-Bgt）以及α-银环蛇毒素的单碘化和双碘化衍生物与来自加州电鳐电板和大鼠脑的膜结合烟碱型乙酰胆碱受体（nAChR）之间的结合相互作用进行了表征。根据所有标准，[3H]-α-Bgt和125I标记的单碘化α-Bgt（[125I]-α-Bgt）对nAChR表现出相当的特异性和亲和力。相比之下，nAChR对125I标记的双碘化α-Bgt（[125I2]-α-Bgt）的亲和力降低，并且[125I2]-α-Bgt-nAChR复合物表现出异常的双相解离动力学。与碘化毒素相比，天然α-Bgt对[125I]-α-Bgt和[125I2]-α-Bgt结合的抑制作用最强。[3H]-α-Bgt是对抑制作用最具抗性的放射性毒素。使用特征明确的化学修饰α-Bgt衍生物可能会识别配体结合的微观异质性和组织特异性受体亚类。
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