一种乳酸菌胞外多糖糖链结构解析

以分离纯化得到的一种嗜热链球菌分泌的胞外多糖EPS03-1gm为研究对象, 采用气相色谱、分光光度及核磁共振技术对该多糖重复单位结构进行了解析. 结果表明, EPS03-1gm的单糖组成是葡萄糖和半乳糖, 不含糖醛酸和蛋白成分, 其重复单位中有4个糖基单元且都是6C糖. DEPT谱说明每个重复单位中有4个CH2, 用二维核磁共振谱和HMQC及HMBC谱分别对4个糖单元中的H和C进行了归属. 确定该多糖重复单位的糖链结构为: →3)-α-D-Galp-(1→3)-β-D-Galf-(1→3)-β-D-Glcp-(1→6)-β-D-Glcp-(1→.

Glycol-unit Structure Identification of a Kind of Exopolysaccharide from a Lactic Acid Bacterium

The structure of exopolysaccharide EPS03-1gm was identified by the technology of GC, UV spectrophotometric analysis and NMR. The EPS03-1gm was separated and purified before analysis which was secreted from S. thermophilus. The results show that the mono-glycos of EPS03-1gm were glucose and galactose and there are no glycol-aldehudic acid or protein ingredient. The 1H NMR made it clear that there were four glycol-cells in each repeat glycol-unit. The DEPT reveals there were four CH2 in every repeat glycol-unit. The positions of H were confirmed by analyzing the TOCSY spectrum. The positions of H and the order of glycol-cell were confirmed by analyzing the HMQC and HMBC spectra. Finally, the glycol-unit structure were fixed on as follows: →3)-α-D-Galp-(1→3)-β-D-Galf-(1→3)-β-D-Glcp-(1→6)-β-D-Glcp-(1→.