小分子苦瓜多糖MCPⅡa的纯化及结构分析

Purification and Structural Analysis of a Polysaccharide from Bitter Gourd(Momordica charantia)

利用酶解结合水溶醇沉提取水溶性的苦瓜多糖(Momordica charantia polysaccharide,MCP),经Sevag法除蛋白、DEAE-纤维素离子交换、Sephadex G-100凝胶过滤获得活性多糖MCPⅡa。由高效凝胶渗透色谱检测可知MCPⅡa为均一多糖,平均分子质量为13.0 k D,单糖组分分析显示其单糖组成为鼠李糖、半乳糖醛酸、半乳糖、木糖和阿拉伯糖(各组分物质的量比为12∶3.05∶19.89∶5.95∶56)。傅里叶红外光谱、核磁共振及刚果红实验发现其存在C1、C2、C3、C5连接,在水溶液中具有稳定的β-三股螺旋构象,扫描电镜下显示其为菱形晶体颗粒。

In this research, a water-soluble polysaccharide(MCP Ⅱa) was extracted from Momordica charantia by cellulase hydrolysis, precipitated with ethanol, and then purified by DEAE-52 cellulose anion-exchange and Sephadex G-100 gel filtration chromatography. The high performance gel permeation chromatography(HPGPC) analysis showed that the average molecular weight of MCP Ⅱa was 13.0 k D. Monosaccharides analysis revealed that the MCP Ⅱa was composed of Rha, Gal A, Gal, Xyl and Ara with a relative molar ratio of 12:3.05:19.89:5.95:56. Infrared(IR) spectrum, 13C-nuclear magnetic resonance(NMR) and Cango-red tests indicated that MCP Ⅱa formed a β-triple helix in aqueous solution and the C1, C2 and C3, C5 positions were its binding sites. Moreover, it existed as a rhombus crystal under a scanning electron microscope.