棉籽分离蛋白的提取及亚基分析

EXTRACTION OF THE COTTONSEED PROTEIN ISOLATE AND SUBUNITS ANALYSIS

采用一定温度的稀碱液对棉籽粕进行处理，在尽量不破坏蛋白的同时降低其中的棉酚含量，进一步制备出分离蛋白．通过正交试验确定最佳提取条件为：pH7～8，温度50℃，时间3h．利用冷冻沉淀、甲醇洗脱、酸沉等工艺处理提取液中的蛋白，用十二烷基硫酸钠聚丙烯酰胺凝胶电泳（SDS～PAGE）对提取过程中棉籽蛋白亚基组成的变化进行分析．结果表明：酸沉分离蛋白中主要为含量60％左右的中低相对分子质量组分，其中pH6．0酸沉蛋白和pH4．5酸沉蛋白20000和14000组分含量有显著差异；甲醇处理后蛋白发生交联，部分亚基聚集不易进行分析，不过棉酚含量显著降低．

The cottonseed meal was processed with dilute alkali at a certain temperature to reduce the gossypol content without destroying the protein, and the protein isolate was further prepared. The optimum extraction conditions were determined by orthogonal test as follows ： pH 7 - 8, temperature 50℃, time 3 h. Protein in the ex- tract solution was obtained by cryoprecipitation, methanol elution and acid precipitation. Sodium dodecyl sulfate -polyacrylamide gel electrophoresis （SDS -PAGE） was used to analyze the change in the composition of cottonseed protein subunits in the extraciton process. The results show that： acid -processed protein isolate mainly contains ingredients of globulin 60%. The proteins （20 000 and 14 000） processed with pH 6.0 acid and pH 4. 5 acid show significant difference in content. Proteins processed by methanol are cross -linked, parts of the subunits can not be analyzed easily due to aggregation, but the content of gossypol is reduced greatly.