大豆特征蛋白的SDS-PAGE研究

A Study on the Characteristic Soybean Protein by SDS-PAGE

大豆蛋白作为乳品中的主要掺假蛋白,对其进行鉴别并建立相应的检测和分析方法,对于健全乳制品安全监管体制,确保消费者的合法权益具有重要的意义。该文利用SDS-PAGE方法对12种不同来源大豆均质浆液中的可溶性蛋白进行分析,并与两种商品大豆蛋白进行比较。经SDS-PAGE电泳分析,这14种大豆蛋白主要包含相对分子质量（简称分子量）为1.90×10^4～8.50×10^4的9组蛋白。每组蛋白的分子量差异较小,相对差值不大于3.3%,而且蛋白条带的相对含量基本相同。发现大豆中蛋白分子量为4.97×10^4、4.17×10^4、3.57×10^4以及1.98×10^4的可溶性蛋白组分,可作为SDS-PAGE鉴别牛乳中掺杂大豆蛋白的特征识别标记,其中4.96×10^4和3.57×10^4的最低检出限可达0.2 g/L。使用光密度仪测定,在大豆浆液蛋白含量0.1～10 g/L范围,定量工作曲线的线性关系较好,R=0.998 1,应用于0.60～8.0 g/L范围测量,相对误差为0.63%～13.3%。

Soybean protein is found in protein adulteration of dairy products recently.In order to improve the oversight system for dairy product and ensure the legal rights and interests of consumers,it is vital to establish a method for the identification and detection of it.In this paper,12 kinds of different sources of soluble homogeneous soy protein slurry were analyzed and compared with the two kinds of commercially available soy protein by SDS-PAGE method.It was found that there were mainly 9 groups of soy proteins with the molecular weight ranging from 1.90 ×10^4 to 8.50 ×10^4 in the 14 kinds of soy.There is little difference in the molecular weight of each group; the relative difference is not more than3.3%.Moreover,the relative content of the protein bands is basically the same.The soy protein molecular weight of 4.97 ×10^4,4.17 ×10^4,3.57 ×10^4 and 1.98 ×10^4 of the soluble protein fraction can be used to identify soy protein adulteration in milk.The detection limit of 4.96 ×10^4 and 3.57 ×10^4was 0.2 g/L.This method had a good linear relativity（R = 0.998 1） in the range from 0.1 to 10 g/L and the relative error is 0.63% ～ 13.3% within 0.60 ～ 8.0 g/L.