Nishiyama Yoshiharu, Kim Ung-Jin, Kim Dae-Young, Katsumata Kyoko S, May Roland P, Langan Paul
School of Agricultural and Life Science, The University of Tokyo, Tokyo 113-8657, Japan.
Biomacromolecules. 2003 Jul-Aug;4(4):1013-7. doi: 10.1021/bm025772x.
Small angle neutron scattering studies have been carried out on cellulose fibers from ramie and Populus maximowicii (cotton wood). Labile hydrogen atoms were replaced by deuterium atoms, in water-accessible disordered regions of the fibers, to increase the neutron scattering contrast between the disordered and crystalline regions. A meridional Bragg reflection, corresponding to a longitudinal periodicity of 150 nm, was observed when scattering collected from hydrogenated and deuterated dry ramie fibers was subtracted. No Bragg reflection was observed with the cotton wood fibers, probably because of lower orientation of the microfibrils in the cell wall. The ramie fibers were then subjected to electron microscopy, acid hydrolysis, gel permeation chromatography, and viscosity studies. The leveling off degree of polymerization (LODP) of the hydrolyzed samples matched exactly the periodicity observed in the diffraction studies. The weight loss related to the LODP was only about 1.5%, and thus, the microfibrils can be considered to have 4-5 disordered residues every 300 residues.
对来自苎麻和大青杨（棉白杨）的纤维素纤维进行了小角中子散射研究。在纤维的水可及无序区域中，不稳定的氢原子被氘原子取代，以增加无序区域和结晶区域之间的中子散射对比度。当从氢化和氘化的干燥苎麻纤维收集的散射相减时，观察到一个对应于150nm纵向周期的子午布拉格反射。棉白杨纤维未观察到布拉格反射，可能是因为细胞壁中微纤丝的取向较低。然后对苎麻纤维进行电子显微镜、酸水解、凝胶渗透色谱和粘度研究。水解样品的聚合度平稳值（LODP）与衍射研究中观察到的周期完全匹配。与LODP相关的重量损失仅约1.5%，因此，可以认为微纤丝每300个残基中有4-5个无序残基。
