作者: H Prinz , A Maelicke
DOI: 10.1016/S0021-9258(17)44451-6
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摘要: We have studied the binding equilibria of two fluorescent ligands and several nonfluorescent cholinergic with purified acetylcholine receptor from Electrophorus electricus. The assay was based on specifically reversible quenching fluorescence observed upon complex formation between protein N-7-(4-nitrobenzo-2-oxa-1,3-diazole)-5-aminopentanoic acid beta-(N-trimethylammonium) ethyl ester. This way, a large body accurate, true equilibrium data obtained. find 1) all compete for same number sites at receptor; 2) agonists half these high affinity other significantly lower affinity; 3) antagonists one 4) in presence disulfide reducing agents, patterns some are changed accordance electrophysiological changes under conditions Rana pipiens Sartorius muscle fibers. Our studies indicate that mechanism ligand recognition is still functional not subject to an intact membrane environment. Furthermore, existence types agonist every molecule excludes most presently discussed two-state models as basis receptor-ligand interaction. To explain sigmoidal dose-response curves, two-site model already sufficient.