Enzymatic fragmentation of carbohydrate moieties of radish arabinogalactan-protein and elucidation of the structures
Enzymatic fragmentation of carbohydrate moieties of radish arabinogalactan-protein and elucidation of the structures
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DOI：
10.1080/09168451.2014.910100
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发表时间：
2014-05-01
影响因子：
1.6
通讯作者：
Tsumuraya, Yoichi
中科院分区：
文献类型：
--
作者：
Shimoda, Ryohei;Okabe, Kohei;Tsumuraya, Yoichi
我们研究了萝卜阿拉伯半乳聚糖蛋白（AGP）的糖部分通过外切-β-（1 -> 3）-半乳聚糖酶的作用释放的L-阿拉伯-半乳寡糖的结构。我们检测到一系列中性β-（1 -> 6）-连接的低聚半乳糖，其形成一个至多达至少19个连续Gal基团的分支，以及相应的在非还原端终止于4-O-甲基-葡萄糖醛酸（4-Me-GlcA）的酸性衍生物。一些寡糖链的聚合度（dp）高于3的中性，和4的酸性低聚物与L-Araf残基进行了修改。酸性四糖4-Me-beta-GlcA-（1 -> 6）[alpha-L-Araf-（1 -> 3）]-beta-Gal-（1 -> 6）-Gal在这些中性和酸性低聚物中被检测为丰富的含L-Araf的寡糖。我们观察到L-阿拉伯半乳糖低聚糖在这些中性和酸性β-（1 -> 6）-半乳糖低聚糖链的不同Gal残基沿着被单糖或二糖L-Araf单元取代，表明这些侧链在长度上高度可变，并且被L-Araf残基不同地取代。
We investigated the structures of L-arabino-galactooligosaccharides released from the sugar moieties of a radish arabinogalactan-protein (AGP) by the action of exo-beta-(1 -> 3)-galactanase. We detected a series of neutral beta-(1 -> 6)-linked galactooligosaccharides forming branches of one to up to at least 19 consecutive Gal groups, together with corresponding acidic derivatives terminating in 4-O-methyl-glucuronic acid (4-Me-GlcA) at the non-reducing end. Some oligosaccharide chains of degree of polymerization (dp) higher than 3 for neutral, and 4 for acidic oligomers were modified with L-Araf residues. The acidic tetrasaccharide 4-Me-beta-GlcA-(1 -> 6)[alpha-L-Araf-(1 -> 3)]-beta-Gal-(1 -> 6)-Gal was detected as an abundant L-Araf-containing oligosaccharide among these neutral and acidic oligomers. A pentasaccharide containing an additional L-Araf group attached to the L-Ara in the tetrasaccharide through an alpha-(1 -> 5)-linkage was also found. We observed L-ara-bino-galactooligosaccharides substituted with single or disaccharide L-Araf units at different Gal residues along these neutral and acidic beta-(1 -> 6)-galactooligosaccharide chains, indicating that these side chains are highly variable in length and substituted variously with L-Araf residues.