Hydration and counterion binding of aqueous acetylcholine chloride and carbamoylcholine chloride. Issue 44 (8th November 2021)

• Record Type: Journal Article
• Authors: Friesen, Sergej; Fedotova, Marina V.; Kruchinin, Sergey E.; Bešter-Rogač, Marija; Podlipnik, Črtomir; Buchner, Richard
• Is Part Of: Physical chemistry chemical physics. Volume 23:Issue 44(2021)
• Page Start: 25086
• Page End: 25096
• Publication Date: 2021-11-08
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/d1cp03543f
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : Weak hydration and weak counterion binding enable Janus behaviour of acetylcholine. Abstract : The hydration and Cl − ion binding of the neurot † ransmitter acetylcholine (ACh + ) and its synthetic analogue, carbamoylcholine (CCh + ), were studied by combining dilute-solution conductivity measurements with dielectric relaxation spectroscopy and statistical mechanics calculations at 1D-RISM and 3D-RISM level. Chloride ion binding was found to be weak but not negligible. From the ∼30 water molecules coordinating ACh and CCh + only ∼1/3 is affected in its rotational dynamics by the cation, with the majority – situated close to the hydrophobic moieties – only retarded by a factor of ∼2.5. At vanishing solute concentration cations and the ∼3–4 H2 O molecules hydrogen bonding to the CO group of the solute exhibit similar rotational dynamics but increasing concentration and temperature markedly dehydrates ACh + and CCh + .