Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education and Yunnan Province, School of Chemical Science and Technology, Yunnan University, Kunming 650091, China; State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China; University of Chinese Academy of Sciences, Beijing 100049, China; Yunnan Institute of Traditional Chinese Medicine and Materia Medica, Kunming 650223, Yunnan, China.
State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China; School of Pharmaceutical Sciences, South-Central University for Nationalities, Wuhan 430074, China.
Carbohydr Polym. 2021 Oct 15;270:118368. doi: 10.1016/j.carbpol.2021.118368. Epub 2021 Jun 24.
Free radical depolymerization is a common method in structural analysis of polysaccharides, the major challenge is the analysis of the cleavage site and characterization of newly formed ends in this reaction. Here, a fucosylated glycosaminoglycan from H. fuscopunctata (HfFG) was depolymerized by HO and a series of oligosaccharides were purified and their structures were elucidated. For non-reducing ends of the trisaccharides were intact GalNAc, the cleavage site should mainly be the β(1,3) linkages between GlcA and GalNAc in the backbone of FG. Meanwhile, the reducing ends of the disaccharides and trisaccharides were almost dicarboxylic acid derivatives of GlcA, possibly arising from oxidative breaking of the CC bond of GlcA at the reducing ends. In addition, glycosidic linkages in D-GalNAc-β(1,4)-D-GlcA and L-FucS-α(1,3)-D-GlcA located at the reducing end could be cleaved, and the released GalNAc were oxidized to N-acetylgalactosaminic acid.
自由基解聚是多糖结构分析中的常用方法，主要挑战在于分析该反应中的断裂位点和新形成末端的特征。在这里，我们用 HO 对来自 H. fuscopunctata（HfFG）的岩藻糖基化糖胺聚糖进行了解聚，分离并纯化了一系列寡糖，并阐明了它们的结构。由于三糖的非还原末端完整的 GalNAc，因此断裂位点应该主要是 FG 主链中 GlcA 与 GalNAc 之间的β(1,3)键。同时，二糖和三糖的还原末端几乎都是 GlcA 的二羧酸衍生物，可能是由于 GlcA 还原末端的 CC 键发生了氧化断裂。此外，位于还原末端的 D-GalNAc-β(1,4)-D-GlcA 和 L-FucS-α(1,3)-D-GlcA 中的糖苷键也可以被切断，释放出的 GalNAc 被氧化为 N-乙酰半乳糖胺酸。
