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. 1979 Aug;76(8):3580–3584. doi: 10.1073/pnas.76.8.3580

Proton magnetic resonance studies of cholinergic ligand binding to the acetylcholine receptor in its membrane environment.

J Miller, V Witzemann, U Quast, M A Raftery
PMCID: PMC383875  PMID: 291025

Abstract

Proton magnetic resonance has been used to monitor binding of choline, a known partial agonist, to acetylcholine receptor-enriched membrane preparations from Torpedo californica electroplax. The interaction between choline and receptor led to a broadening of the resonance of the choline methyl groups and this effect was reversed by alpha-bungarotoxin, a quasi-irreversible antagonist of the acetylcholine receptor. From the concentration dependence of line broadening the equilibrium dissociation constant for choline was obtained (Kd = 190 +/- 65 microM). The temperature dependence of the parameters observed in the choline titrations gave an enthalpy of binding delta H less than 1.5 kcal/mol and allowed estimates for the dissociation rate constant of the receptor-choline complex (kdiss greater than 1.6 x 10(3) S(1) and the respective activation energy, Ea (Kdiss) approximately 5.5 kcal/mol. The association of other ligands with the membrane-bound receptor could also be studied by observing effects of varying concentrations of such ligands on the choline methyl group linewidth at a constant choline concentration.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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