Vibrational spectroscopic approach to the study of acetylcholine and related compounds

The present review reports the coordinated application of three spectroscopic methods (Raman, infrared(IR) and inelastic electron tunneling spectroscopy (IETS)) in the study of the conformation of Ach and some analogues (beta-MeAch, Mu and Nic) in solid state, aqueous solution and in interaction with a surface. Useful correlated information is obtained by Raman and IR spectroscopies on the conformational possibilities of these molecules in transition from solid state to aqueous solution. With this information in hand as well as on the basis of Raman and IR study of the nonenzymatic hydrolysis of Ach, the first detailed experimental investigation of the interaction of Ach and beta-MeAch adsorbed on a surface (A1203) is realised by the IETS method. The results are used to discuss an interaction analogous to that of Ach with receptor and another one analogous to that of Ach and AchE.