提取条件对大豆β-伴球蛋白(7S)得率及纯度的影响

Isolation of β-conglycinin(7S):effect of extraction conditions on its yield and purity

以低脂质含量豆粕为原料,探讨了大豆β-伴球蛋白(7S)分级分离过程中还原剂、冷沉时间和pH对其得率及纯度的影响。与亚硫酸氢钠或二硫苏糖醇相比,在提取液中添加β-巯基乙醇,7S得率与纯度均最高。在蛋白提取的冷沉阶段,随着冷沉时间的延长,后续分离所得7S得率持续降低,而纯度逐渐提高,当冷沉时间超过12 h以后,7S纯度增速放缓,此时在P≥0.05水平上,总的巯基与二硫键含量略有差异。在7S酸沉阶段,采用pH 4.70酸沉时7S得率与纯度均最佳,这与目前文献报道的7S分离多采用pH 4.80的酸沉条件有差异,原因有待进一步探讨。

The influences of reducing agent, cryoprecipitation time and pH on the yield and purity of β- conglycinin （7S） during fractionation were evaluated with low -fat soybean meal as raw material. Com- pared with sodium bisulfite or dithiothreitol, the yield and purity of 7S were the highest whenβ--mercap- toethanol was added to the protein extracting solution. Prolonging cryoprecipitation time in the cryoprecip- itation stage, the yield of 7S decreased continuously, but the purity increased gradually. When cryopre- cipitation time exceeded 12 h, the increment velocity of 7S purity slowed down, while there was slight difference in total sulfhydryl and disulfide content on P≥0.05 level. The yield and purity of 7S were the highest when the pH of the protein extract was adjusted to 4. 70 on the precipitation stage, which was dif- ferent from the cited literature in pH 4. 80. The reason for that would be investigated further.