麦胚球蛋白的分离制备及理化性质研究

Study on Preparation and Physicochemical Properties of Wheat Germ Globulins

采用Osborne分级分离的方法制备得到麦胚球蛋白,获得的球蛋白的蛋白质含量为87.3%(干基),得率为5.8g/100g脱脂麦胚粉,其在脱脂麦胚粉蛋白中的构成比例为15.6%。氨基酸分析表明,除蛋氨酸略低于FAO/WHO的推荐值外,其它七种必需氨基酸都高于或接近FAO/WHO的推荐值;另外,谷氨酸、精氨酸、天冬氨酸和丙氨酸的含量十分丰富,而胱氨酸和半胱氨酸的含量最低。还原的十二烷基硫酸钠-聚丙烯酰胺电泳(SDS-PAGE)表明,麦胚球蛋白主要有六条谱带,其分子量依次为57.8kDa、41.8kDa、38.7kDa、24.1kDa、16.5kDa和14.3kDa。差示扫描量热仪(DSC)分析表明麦胚球蛋白干粉和稀溶液的变性温度分别为98.2℃和83.8℃。

Wheat germ globulins were extracted from defatted wheat germ flour by Osborne fractionation. The yield of globulin product is 5.8g/100g defatted wheat germ flour. The obtained globulin product possesses a protein content of 87.3% （dry basis） which is 15.6% of total amount of the defatted wheat germ protein. Compared with FAO/WHO reference pattern, the globulins possesses adequate amounts of essential amino acids for child and adult nutrition except the slightly inadequate methionine. It is rich in Glu, Arg, Asp and Ala, while relatively low in cystine. Reduced dodecyl sulfate- polyacrylamide gel electrophoresis （SDS -PAGE ） reveals that the globulins are mainly composed of six bands with molecular weights of 57.8kDa, 41.8kDa, 38.7kDa, 24. 1kDa, 16.5kDa, and 14.3kDa, respectively. DSC （differential scanning calorimetry） analysis shows that the denaturation temperatures of powder and dilute solution of the globulins are 98.2℃ and 83.8℃, respectively.