Department of Biomaterial and Life Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo, Japan.
Biomacromolecules. 2012 Jan 9;13(1):288-91. doi: 10.1021/bm201512t. Epub 2011 Dec 28.
The hydrogen bonding arrangement in anhydrous β-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from a sample prepared from the bathophilous tubeworm Lamellibrachia satsuma in which all labile hydrogen atoms had been replaced by deuterium.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 acetamide groups were directly located in Fourier maps synthesized using phases calculated from the X-ray structure and amplitudes measured from the neutron data. The hydrogen bond arrangement in the refined structure is in general 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 Å and a hydrogen bond angle of 171°.
无水β-壳聚糖（N-乙酰葡萄糖胺的均聚物）中的氢键排列结构通过中子纤维衍射直接确定。数据是从一种从嗜碱性管蠕虫 Lamellibrachia satsuma 中提取的样本中收集的，其中所有不稳定的氢原子都被氘取代。在傅立叶图谱中，羟基和乙酰胺基团上氘原子的初始位置是根据 X 射线结构计算的相位和从中子数据测量的幅度直接定位的。在精修结构中，氢键排列与基于 X 射线结构的预测基本一致：O3 向同一链中相邻残基的 O5 环氧原子提供氢键；N2 和 O6 向相邻链的相同羰基氧 O7 提供氢键。分子内的 O3···O5 氢键具有最有利的能量几何形状，氢与受体的距离为 1.77 Å，氢键角度为 171°。
