香菇蛋白的分级纯化和结构分析

香菇粉经10℃pH 10的水提取制备香菇蛋白,得率13.1%,其蛋白含量47.5%,多糖含量24.2%.香菇蛋白经DEAE Sepharose CL-6B柱层析分级得5个级分,收集级分F1、F2、F3、F4,它们都是由蛋白和多糖构成的复合物.Sepharose CL-6B凝胶色谱显示,F2和F4的分子量分布较为均匀,且以蛋白为主,多糖含量很低;F3主要由两个分子量不同的蛋白级分构成,含有一定的多糖;F1中多糖含量较高,蛋白含量较少,且多糖分子量分布均匀.香菇蛋白的分子量主要集中在20 kDa～40 kDa之间.F1、F3、F4都属于酸性蛋白质,含有除色氨酸之外的7种必需氨基酸,除蛋氨酸含量较低外,其余必需氮基酸含量接近,且赖氨酸含量较高.红外光谱分析表明,香菇蛋白的二级结构主要为α-螺旋和无规卷曲.

Fractionation and Structure of Protein from Lentinus edodes

Powder of Lentinus edodes was treated with water of 10℃ and pH 10 to extract the protein of Lentinus edodes (PLE).The yield of PIE was 13.1%,and its protein content was 47.5% and polysaccharide content was 24.2%.PLE was graded into five fractiona by chromatography on a DEAE Sepharose CL-6B Column.Fractions F1,F2,F3 and F4 were collected,which all were the complex of protein and polysaccharide.Gel filtration chromatography of Sepharose CL-6B showed that molecular weight(Mw)distribution of F2 and F4 was symmetrical,and they contained mainly protein and little polysaccharide.F3 was composed of two protein fractions with different Mw and contained some polysaccharide.F1 contained more polysaccharide and less protein and its Mw distribution was symmetrical.Mw of PLE was mainly between 20-40 kDa.F1,F2 and F3 were belonged to acidic proteins.They contained seven kinds of essential amino acids except Trp.Besides of Met with less content,other amino acids had almost content and the content of Lys was higher.IR spectra showed that secondary structure of PLE mainly was α-helix and random coil.