The hydration of the neurotransmitter acetylcholine in aqueous solution
The hydration of the neurotransmitter acetylcholine in aqueous solution
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DOI：
10.1529/biophysj.106.089185
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发表时间：
2006-09-01
影响因子：
3.4
通讯作者：
Finney, J. L.
中科院分区：
文献类型：
--
作者：
Hulme, E. C.;Soper, A. K.;Finney, J. L.
用氢同位素取代增强的中子衍射研究了水溶液中乙酰胆碱分子离子周围的水结构。结果表明，最近邻的水分子在周围的区域的三甲基铵头基位于环周围的中心氮原子或碳原子之间，形成鞘周围的鎓基团。此外，该空腔中的水分子不与鎓基团键合，而是与周围水性环境中的水分子形成氢键。考虑到在结合状态下的鎓头基必须完全去溶剂化，鎓头基和周围的水溶剂之间没有键合可能选择性地有利于受体位点中的乙酰胆碱结合。远离头基，观察到明显的氢键的水的羰基氧，但不醚氧在乙酰胆碱链。
Neutron diffraction augmented with hydrogen isotope substitution has been used to examine the water structure around the acetylcholine molecular ion in aqueous solution. It is shown that the nearest-neighbor water molecules in the region around the trimethylammonium headgroup are located either in a ring around the central nitrogen atom or between the carbon atoms, forming a sheath around the onium group. Moreover the water molecules in this cavity do not bond to the onium group but rather form hydrogen bonds with water molecules in the surrounding aqueous environment. Given that in the bound state the onium headgroup must be completely desolvated, the absence of bonding between the onium headgroup and the surrounding water solvent may be selectively favorable to acetylcholine-binding in the receptor site. Away from the headgroup, pronounced hydrogen-bonding of water to the carbonyl oxygen is observed, but not to the ether oxygen in the acetylcholine chain.