转谷氨酰胺酶催化大豆蛋白和乳清蛋白合成耐热性聚合蛋白

摘要

Synthesis of biopolymers by soybean protein with whey protein using transglutaminase (TG-B)was studied.The extent of polymerization was determined by SDS-PAGE associated with gel image analysis. Differential scanning calorimetry (DSC) was used to determine thermal properties of the biopolymers.The results showed TG-B catalyzed the formation of heterologous and homologous biopolymers from soybean defatted meal and whey protein. SDS-PAGE demonstrated that the biopolymers mostly formed by soybean 11S globulin with α-lactalbumin and β-lactoglobulin when TG-B was added. The optimum condition of this reaction were as follows:pH6-7,30～45℃，TG-B added at 10mg/g protein (6 units/g protein).After polymerization at this condition,the relative content of biopolymers reached their maximum,30%.The biopolymers did not show any endothermic peak of denaturation up to 132℃,indicating that polymerization improved heat stability of soybean protein.The result also showed that the solubility of the biopolymers kept constant at pH3.5～4.0,which may be useful for functionality of acid protein beverages.%用商品级转谷氨酰胺酶(TG-B)聚合大豆蛋白和乳清蛋白形成高耐热、耐酸的蛋白聚合物。蛋白聚合物的合成量由SDS-PAGE电泳结合凝胶成像分析测定；蛋白聚合物的耐热性用差示扫描量热法(DSC)测定；蛋白聚合物的酸溶解性用双缩脲法测定。结果表明TG-B聚合大豆蛋白和乳清蛋白形成的蛋白聚合物的最适条件为：pH为6～7；反应温度30℃～45℃，反应时间4h，加酶量为6当量单位/g蛋白，在此条件下蛋白聚合物的转化量可达30%，所合成蛋白聚合物可耐130℃的热处理而不发生变性；并在pH 3.2～4.3范围不发生沉淀。