Cy3-3-acylcholine: A fluorescent analogue of acetylcholine for single molecule detection

We synthesized a novel fluorescent analogue of acetylcholine, Cy3-3-acylcholine. The molecular weight of the products agreed with structural predictions. Discrete intensity changes of fluorescent spots due to a single ligand binding/unbinding to nAChR were visualized by TIRF microscopy. The agonist effect of the Cy3-3-acylcholine on nicotinic acetylcholine receptor (nAChR) was confirmed electrophysiologically. This newly synthesized fluorescent analogue will enable us to conduct more elaborate studies on single channel interaction processes between nAChR and ligands.