Burgen_1989_Trends.Pharmacol.Sci_Suppl_1

Since the amino acid sequences for several muscarinic and adrenergic receptors are known, an attempt was made to correlate side chain hydrophobicity surrounding the aspartate anionic groups with binding structure-activity relationships. No positive correlation was found, suggesting that secondary binding effects of head group substituents are non-local. Displacement of aspartate ionization is unlikely to be due to such neighbour effects.