Institute of Chemistry, Federal Research Center "Komi Science Center of the Ural Branch of the Russian Academy of Sciences", Pervomaiskaya St. 48, Syktyvkar 167982, Russia.
Institute of Chemistry, Federal Research Center "Komi Science Center of the Ural Branch of the Russian Academy of Sciences", Pervomaiskaya St. 48, Syktyvkar 167982, Russia.
Carbohydr Polym. 2022 Feb 1;277:118832. doi: 10.1016/j.carbpol.2021.118832. Epub 2021 Oct 30.
In this study, by NMR spectroscopy, first was proved that the pectic polysaccharides of Abies sibirica are covalently bound to arabinoglucuronoxylan (AGX). Namely, AGX is attached at the 4th position to the 1,2,4-α-L-Rha residues of the RG-I main chain, indicating the following fragment: …→2)-[(2,4-β-D-Xylp)-(1→4)]-[(α-D-GalpA-(1→2)]-α-L-Rhap-(1→4)-α-D-GalpA-(1→…. We present direct evidence of covalent attachment between C1 of 1,2,4-β-D-Xylp from arabinoglucuronoxylan and С4 of 1,2,4-α-L-Rhap from RG-I of pectin by detailed 2D NMR analyses. It can be concluded that the 1,2,4-α-L-Rhap residues, were substituted at the 4th position by 1,5-α-L-arabinan or 1,4-β-D-galactan or AGX. The discovery of this interglycosidic linkage between xylan and pectin contradicts the classical model of the cell wall, which describes networks of binding glycans and pectic polysaccharides as separate and independent of one another. We can conclude that pectin undoubtedly plays a more important supporting and cross-linking role in the cell wall than is commonly thought.
在这项研究中，通过核磁共振波谱法首次证明，西伯利亚冷杉的果胶多糖与阿拉伯半乳聚糖木聚糖（AGX）发生共价结合。也就是说，AGX 连接在 RG-I 主链 1,2,4-α-L-Rha 残基的第 4 位上，表明存在以下片段：…→2)-[(2,4-β-D-Xylp)-(1→4)]-[(α-D-GalpA-(1→2)]-α-L-Rhap-(1→4)-α-D-GalpA-(1→…。我们通过详细的二维 NMR 分析提供了阿拉伯半乳聚糖木聚糖 1,2,4-β-D-Xylp 的 C1 与果胶 RG-I 中的 1,2,4-α-L-Rhap 的 C4 之间共价连接的确切证据。可以得出结论，1,2,4-α-L-Rhap 残基被 1,5-α-L-阿拉伯聚糖或 1,4-β-D-半乳糖聚糖或 AGX 取代第 4 位。木聚糖和果胶之间这种糖苷键的发现与细胞壁的经典模型相矛盾，该模型描述了结合聚糖和果胶多糖的网络彼此独立且互不相关。我们可以得出结论，果胶在细胞壁中无疑发挥着比普遍认为的更重要的支撑和交联作用。
