The Solute-Solvent System: Solvent Constraints on the Conformational Dynamics of Acetylcholine
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- 作者：Giulio Vistoli ; Alessandro Pedretti ; Luigi Villa ; and Bernard Testa
- 刊名：Journal of the American Chemical Society
- 出版年：2002
- 出版时间：June 26, 2002
- 年：2002
- 卷：124
- 期：25
- 页码：7472 - 7480
- 全文大小：287K
- 年卷期：v.124,no.25(June 26, 2002)
- ISSN：1520-5126
文摘
The objective of this study was to determine if and how a solvent influences internal motions ina solute molecule. Acetylcholine was chosen as the object of study given its interesting molecular structureand major biological significance. Molecular dynamics simulations were carried out in the vacuum (10 ns),water (5 ns), methanol (5 ns), and octanol (1.5 ns). Seven clusters of conformers were identified, namely,+g+g, -g-g, +gt, -gt, t+g, t-g, and tt, where the gauche and trans labels refer to the dihedral angles
2 and 3, respectively. As expected, the relative proportion of these conformational clusters was highlysolvent-dependent and corresponded to a progressive loss of conformational freedom with increasingmolecular weight of the solvent. More importantly, the conformational clusters were used to calculateinstantaneous and median angular velocity (
and M, respectively) and instantaneous and median angularacceleration (
and M, respectively). Angular velocity and angular acceleration were both found to decreasemarkedly with increasing molecular weight of the solvent, i.e., vacuum (
= 1) > water > methanol >octanol. The decrease from the vacuum to octanol was ~40% for 2 and ~60% for 3. Such solvent-dependent constraints on a solute's internal motions may be biologically and pharmacologically relevant.
2 and 3, respectively. As expected, the relative proportion of these conformational clusters was highlysolvent-dependent and corresponded to a progressive loss of conformational freedom with increasingmolecular weight of the solvent. More importantly, the conformational clusters were used to calculateinstantaneous and median angular velocity ( and M, respectively) and instantaneous and median angularacceleration ( and M, respectively). Angular velocity and angular acceleration were both found to decreasemarkedly with increasing molecular weight of the solvent, i.e., vacuum ( = 1) > water > methanol >octanol. The decrease from the vacuum to octanol was ~40% for 2 and ~60% for 3. Such solvent-dependent constraints on a solute's internal motions may be biologically and pharmacologically relevant.