低分子量白籽仁多糖的制备及结构研究

Preparation of low molecular-weight polysaccharide of endosperm of Gleditsia japonica var.delavayi seeds and its structure determination

采用酶法对大分子量的白籽仁多糖(Polysaccharide of endosperm of Gleditsia japonica var. delavayi seeds,EGSP)进行降解,得到一种低分子量白籽仁多糖(Low molecular-weight EGSP,L-EGSP)。结合气相色谱、甲基化分析、红外及核磁共振等方法对L-EGSP的精细结构进行了研究。结果显示L-EGSP相对分子质量约为4.3kDa,主要由甘露糖和半乳糖组成,甘露糖/半乳糖=1.93∶1;甲基化结果表明,L-EGSP的主链由甘露糖通过β-1,4-糖苷键连接,部分主链甘露糖的C_6位置被半乳糖取代,以α-1,6-糖苷键相连,形成侧链;精细结构的计算结果显示,L-EGSP的结构中存在两个半乳糖连续取代的非平滑区域。L-EGSP分子结构的测定为探索多糖的结构-活性关系奠定了基础,有助于指导功能性天然多糖的有效筛选。

The high molecular-weight polysaccharide of endosperm of G.japonica var.delavayi seeds(EGSP)was degraded by enzymatic hydrolysis to obtain a low molecular-weight EGSP(L-EGSP).The?ne structure of L-EGSP was studied by gas chromatography,methylation analysis,infrared and nuclear magnetic resonance.The results showed that the relative molecular mass of L-EGSP was about 4.3 kDa,mainly composed of mannose and galactose,and the ratio of mannose and galactose was 1.93.The methylation results indicated that the main chain of L-EGSP was composed of mannose throughβ-1,4-glycosidic linkage,the C6 position of some main chain mannose is replaced by galactose,and the side chain is formed by theα-1,6-glycosidic bond;the calculation results of the?ne structure showed that there were two non-smooth areas replaced continuously by the galactose.The determination of L-EGSP molecular structure laid a foundation for exploring the structure-activity relationship of polysaccharides,and helped to guide the effective screening of natural functional polysaccharides.