Direct Determination of the Hydrogen Bonding Arrangement in Anhydrous β-Chitin by Neutron Fiber Diffraction
Direct Determination of the Hydrogen Bonding Arrangement in Anhydrous β-Chitin by Neutron Fiber Diffraction
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DOI：
10.1021/bm201512t
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发表时间：
2012-01-01
影响因子：
6.2
通讯作者：
Wada, Masahisa
中科院分区：
文献类型：
--
作者：
Sawada, Daisuke;Nishiyama, Yoshiharu;Wada, Masahisa
用中子纤维衍射法直接测定了N-乙酰氨基葡萄糖的均聚物--无水β-甲壳素中的氢键排列。数据是从一个样品中收集的，该样品是从嗜深管虫Lamellibrachia satsuma中制备的，其中所有不稳定的氢原子都被氘取代。氘原子的羟基和acetarnide基团上的初始位置直接位于傅立叶映射合成使用从X射线结构和中子数据测量的振幅计算的相位。改进结构中的氢键排列与基于X射线结构的预测基本一致：O3与同一链中相邻残基的O 5环氧原子形成氢键; N2和O 6与相邻链中相同的羰基氧O 7形成氢键。分子内O3... O 5氢键具有能量最大的有利几何形状，氢到受体的距离为1.77埃，氢键角为171度。
The hydrogen bonding arrangement in anhydrous beta-chitin, a homopolymer of N-acetylglucosamine, was directly determined by neutron fiber diffraction. Data were collected from a sample prepared from the bathophilous tubeworm Lamellibrachia satsuma in which all labile hydrogen atoms had been replaced by deuterium. Initial positions of deuterium atoms on hydroxyl and acetarnide groups were directly located in Fourier maps synthesized using phases calculated from the Xray structure and amplitudes measured from the neutron data. The hydrogen bond arrangement in the refined structure is in general it agreement with predictions based on the X-ray structure: O3 donates a hydrogen bond to the O5 ring oxygen atom of a neighboring residue in the same chain; N2 and O6 donate hydrogen bonds to the same carbonyl oxygen O7 of an adjacent chain. The intramolecular O3 ... O5 hydrogen bond has the most energetically, favorable geometry with a hydrogen to acceptor distance of 1.77 angstrom and a hydrogen bond angle of 171 degrees.