Pennsylvania State University, University Park, Pennsylvania 16802, United States.
Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom.
Biomacromolecules. 2024 Oct 14;25(10):6357-6366. doi: 10.1021/acs.biomac.4c00995. Epub 2024 Aug 29.
Assessing the number of glucan chains in cellulose microfibrils (CMFs) is crucial for understanding their structure-property relationships and interactions within plant cell walls. This Review examines the conclusions and limitations of the major experimental techniques that have provided insights into this question. Small-angle X-ray and neutron scattering data predominantly support an 18-chain model, although analysis is complicated by factors such as fibril coalescence and matrix polysaccharide associations. Solid-state nuclear magnetic resonance (NMR) spectroscopy allows the estimation of the CMF width from the ratio of interior to surface glucose residues. However, there is uncertainty in the assignment of NMR spectral peaks to surface or interior chains. Freeze-fracture transmission electron microscopy images show cellulose synthase complexes to be "rosettes" of six lobes each consistent with a trimer of cellulose synthase enzymes, consistent with the synthesis of 18 parallel glucan chains in the CMF. Nevertheless, the number of chains in CMFs remains to be conclusively demonstrated.
评估纤维素微纤丝（CMFs）中的葡聚糖链数量对于理解其结构-性能关系以及在植物细胞壁内的相互作用至关重要。本综述考察了主要实验技术的结论和局限性，这些技术为解决这一问题提供了重要的见解。小角 X 射线和中子散射数据主要支持 18 链模型，尽管分析受到纤维合并和基质多糖结合等因素的影响。固态核磁共振（NMR）光谱可根据内部和表面葡萄糖残基的比值来估算 CMF 的宽度。然而，NMR 光谱峰的归属存在不确定性，即表面链或内部链。冷冻断裂透射电子显微镜图像显示纤维素合酶复合物为每个包含六个叶瓣的“玫瑰花结”，这与纤维素合酶三聚体一致，与 CMF 中 18 条平行葡聚糖链的合成一致。然而，CMFs 中的链数仍有待定论。
