Carbohydrate Polymers ( IF 11.2 ) Pub Date : 2020-03-28 , DOI: 10.1016/j.carbpol.2020.116212 Ming-Zhao Xiao , Wei-Jing Chen , Xue-Fei Cao , Yue-Ying Chen , Bao-Chen Zhao , Zhi-Hua Jiang , Tong-Qi Yuan , Run-Cang Sun
In this study, the cellulose and hemicelluloses in heartwood, sapwood, and bark of E. urophylla × E. grandis were comprehensively investigated. The ultrastructural topochemistry of carbohydrates in cell walls was examined in situ by confocal Raman microscopy. Cellulose and alkali-extractable hemicelluloses samples were isolated from different tissues and comparatively characterized by compositional carbohydrate analyses, determination of molecular weights, FT-IR spectroscopy, and XRD and NMR techniques. It was found that among all of the samples, heartwood cellulose had the highest molecular weight as well as the lowest degree of crystallinity. Meanwhile the hemicelluloses in heartwood had higher xylose content, lower degree of branching, slightly lower molecular weights but narrower polydispersity than those in sapwood. The eucalyptus hemicelluloses mainly consisted of (1→4)-β-D-xylan backbone with glucuronic acid side chains. Furthermore, the hemicelluloses isolated from sapwood had a higher degree of substitution with terminal galactose than those isolated from heartwood and bark.
中文翻译:
揭示桉树心材,边材和树皮中碳水化合物的异质性
本研究对尾叶大肠埃希菌×大叶大肠埃希菌的心材,边材和树皮中的纤维素和半纤维素进行了全面研究。原位检查细胞壁中碳水化合物的超微结构通过共聚焦拉曼显微镜。从不同组织中分离出纤维素和碱可提取的半纤维素样品,并通过成分碳水化合物分析,分子量测定,FT-IR光谱以及XRD和NMR技术进行比较表征。发现在所有样品中,心材纤维素具有最高的分子量和最低的结晶度。同时,心材中的半纤维素与边材相比具有较高的木糖含量,较低的支化度,较低的分子量和较窄的多分散性。桉树半纤维素主要由(1→4)-β- D组成-带有木糖醛酸侧链的木聚糖骨架。此外,与从心材和树皮分离的半纤维素相比,从边材分离的半纤维素具有更高的末端半乳糖取代度。