| Abstract
| - Structural information on acetylcholine and its two agonists, nicotine, and muscarine has beenobtained 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 isolatedspecies. A clear signature of the shift of protonation site in nicotine ions is provided by the striking changeof their infrared spectrum induced by hydration. On the contrary, structures of muscarine ions are onlyslightly influenced by the presence of water.
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