This paper investigates why nicotine selectively activates neuronal and not muscular acetylcholine receptors, finding that a strong cation–π interaction, and also a hydrogen bond, form between nicotine and a specific tryptophan residue in receptors composed of α4 and β2 subunits — the subunit combination thought to underlie nicotine addiction. Muscle-type receptors also contain this tryptophan residue, but the cation–π interaction does not exist and the hydrogen bond is weaker, apparently due to the overall shape of the binding pocket.
- Xinan Xiu
- Nyssa L. Puskar
- Dennis A. Dougherty