title: Experimental observation of the transition between gas-phase and aqueous solution structures for acetylcholine, nicotine, and muscarine ions.
abstract: Structural information on acetylcholine and its two agonists, nicotine, and muscarine has been obtained from the interpretation of infrared spectra recorded in the gas-phase or in low pH aqueous solutions. Simulated IR spectra have been obtained using explicit water molecules or a polarization continuum model. The conformational space of the very flexible acetylcholine ions is modified by the presence of the solvent. Distances between its pharmacophoric groups cover a lower range in hydrated species than in isolated species. A clear signature of the shift of protonation site in nicotine ions is provided by the striking change of their infrared spectrum induced by hydration. On the contrary, structures of muscarine ions are only slightly influenced by the presence of water.
authors.affiliation: Laboratoire de Physique des lasers, UMR 7538 CNRS, Université Paris 13, 93430 Villetaneuse, France.
authors.forename: Mahamadou
authors.initials: M
authors.lastname: Seydou
authors.forename: Gilles
authors.initials: G
authors.lastname: Grégoire
authors.forename: Jean
authors.initials: J
authors.lastname: Liquier
authors.forename: J
authors.initials: J
authors.lastname: Lemaire
authors.forename: Jean Pierre
authors.initials: JP
authors.lastname: Schermann
authors.forename: Charles
authors.initials: C
authors.lastname: Desfrançois
mesh_terms: D000109:Acetylcholine / Q000737:chemistry*; D005740:Gases / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007477:Ions / Q000737:chemistry; D008958:Models, Molecular; D009116:Muscarine / Q000737:chemistry*; D009538:Nicotine / Q000737:chemistry*; D044367:Phase Transition; D012996:Solutions / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D005740:Gases; D007477:Ions; D012996:Solutions; D014867:Water; D009538:Nicotine; D009116:Muscarine; D000109:Acetylcholine