黑乳海参 FG 及其解聚产物的结构解析与抗凝活性分析

	黑乳海参 FG 及其解聚产物的结构解析与抗凝活性分析; Chemical Structures and Anticoagulant Activity of FG from Holothuria nobilis and Its Depolymerized Products
	李姗霓
导师	赵金华
摘要	Fucosylated glycosaminoglycan (FG) is a glycosaminoglycan (GAG) derivative containing a branched glycosyl group, that is unique to echinoderms. In terms of structure, after years of research, FG was generally considered to consist of the disaccharide repeating units of 4-linked β-D-glucuronic acid (GlcUA) and 3-linked N-acetyl-β-D-galactosamine (GalNAc), and L-fucose as branches linked to GlcUA on O-3. FG is an acidic polysaccharide with a large number of sulphate substitutions on its glycosyl groups (mainly on GalNAc and Fuc), and the sulphate substitution forms are diverse. As a macromolecule, due to the large molecular mass, elucidating the precise structures of FG is still challenging. Until now, the precise chemical structure of the natural FG, especially the one with complex branches substituted, remains in doubt.To investigate the exact structure of complex FG, FGs from different sea cucumbers were screened. Preliminary NMR analyses of the prototype FGs revealed the possible presence of complicated side-chain substitutions in FG from Holothuria nobilis (HnFG). In summary, this thesis has systematically analyzed the physicochemical properties of HnFG. The branches (the monosaccharides Fuc2S4S-ol, Fuc3S4S-ol, Fuc3S-ol, Fuc4S-ol and the disaccharides D-GalNAc4S6S-α1,2-L-Fuc3S-ol and D-α-GalNAc4S6S-(1,2)-L-α-Fuc-ol) in HnFG were obtained after mild acid hydrolysis. It was the first discovery of the disaccharide D-GalNAc4S6S-α1,2-L-Fuc3S-ol in mild acid hydrolysate product, tentatively indicating the presence of a unique disaccharide branch in HnFG. Furthermore, HnFG was depolymerized using the β-elimination depolymerization method and the obtained depolymerization products were further purified by GPC and SAX-HPLC to obtain a series of oligosaccharides 1-16. The structures of 1-16 were determined by resolving the NMR spectra and MS data, and the results showed that the oligosaccharide side chains contained both monosaccharides (Fuc) and disaccharides (D-GalNAc-α1,2-L-Fuc) and a variety of sulfated substitutions, including Fuc3S4S, Fuc2S4S,Fuc4S, GalNAc4S6S-α1,2-L-Fuc3S and GalNAc4S-α1,2-L-Fuc3S, thus identifying for the first time the presence of a novel disaccharide in HnFG. In addition, partial reducing end sugar residues (GlcUA-ol) in some of the oligosaccharides were sulfated at the O-2 position. Combination with the analysis of its peroxide depolymerized products, the precise chemical structure of HnFG was deduced as {4)-[D-GalNAcR1-(α1,2)-L-Fuc3S-(α1,3)-]-D-GlcUAR2-(β1,3)-D-GalNAc4S6S- (β1,}m-{4)-[L-FucR3-(α1,3)-]-D-GlcUAR2-(β1,3)-D-GalNAc4S6S-(β1,}n, in which R1 represented 4S or 4S6S, while R2 represented 2S or 0S individually, and R3 represented 3S4S, 2S4S, 4S or 3S. The side chains include about 2/3 sulfated monosaccharide side chains (Fuc2S4S, Fuc3S4S, and Fuc4S), and about 1/3 disaccharide side chains (D-GalNAc4S-α1,2-L-Fuc3S & D-GalNAc4S6S-α1,2-L-Fuc3S). This was the first discovery of disaccharide branches .
	2021-11
文献类型	学位论文
条目标识符	http://ir.kib.ac.cn/handle/151853/74535
专题	昆明植物所硕博研究生毕业学位论文
推荐引用方式 GB/T 7714	李姗霓. 黑乳海参 FG 及其解聚产物的结构解析与抗凝活性分析, Chemical Structures and Anticoagulant Activity of FG from Holothuria nobilis and Its Depolymerized Products[D],2021.

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