基于荧光猝灭法的复合GA/EGCG与热变性乳清蛋白相互作用机制

Mechanism of interaction between composite GA/EGCG and heat-denatured whey protein by fluorescence quenching

目的:开发新型食品功能因子载体,有效调控载体在加工、运输和储存过程中功能因子的释放特性。方法:在不同温度(298.2,304.2,310.2 K)下,采用不同摩尔比(1∶0,3∶1,1∶1,1∶3,0∶1)复配的没食子酸(GA)和表没食子儿茶素没食子酸酯(EGCG)与热变性乳清蛋白(HWPI)之间相互作用,利用荧光猝灭法探究其相互作用机制。结果:与GA相比,EGCG与HWPI的亲和性更强,二者共存时,互相抑制彼此与HWPI的结合,结合常数均减小,亲和性降低;EGCG与HWPI的预先结合会促进低浓度、却抑制高浓度GA与HWPI的结合,而GA与HWPI的预先结合会抑制EGCG与HWPI的进一步结合。GA、EGCG与HWPI结合主要驱动力为离子作用力和疏水作用力。与单一多酚体系相比,GA/EGCG(3∶1)与HWPI反应后,体系内离子作用力和疏水作用力增强;GA/EGCG(1∶1)和GA/EGCG(1∶3)与HWPI的体系内主要以疏水相互作用为驱动力。结论:GA和EGCG与HWPI三者之间发生竞争关系;GA/EGCG与HWPI的主要相互作用力与多酚复配比例有关,与二元体系相比,GA/EGCG(3∶1)与HWPI的三元体系内离子作用力和疏水作用力最大。

Objective:This study aimed to develop a new carrier system for food functional factors that can effectively regulate the release characteristics during processing,transportation,and storage.Methods:The interaction mechanism between gallic acid(GA)and epigallocatechin gallate(EGCG),which were combined at different molar ratios(1∶0,3∶1,1∶1,1∶3,0∶1),with heat-denatured whey protein isolate(HWPI)was investigated at various temperatures(298.2,304.2,310.2 K)using a fluorescence quenching method.Results:The results showed that compared with GA,EGCG had a stronger affinity for HWPI,and when they coexisted,they inhibited each other's binding to HWPI,resulting in decreased binding constants and reduced affinity.Pre-binding of EGCG to HWPI promoted the binding of low concentrations of GA to HWPI,but inhibited the binding of high concentrations of GA to HWPI,pre-binding of GA to HWPI inhibited further binding of EGCG to HWPI.The primary driving forces for binding GA,EGCG,and HWPI were ionic and hydrophobic forces.Compared with the single polyphenol system,the GA/EGCG(3∶1)system had increased ionic and hydrophobic forces in the HWPI reaction,while the GA/EGCG(1∶1)and GA/EGCG(1∶3)systems mainly used hydrophobic interactions as the driving force in the HWPI system.Conclusion:This study demonstrates a competitive relationship among GA,EGCG,and HWPI.The main interaction forces between GA/EGCG and HWPI depend on the composition ratio of the polyphenol complex.Compared to the binary system,the ternary system of GA/EGCG(3∶1)with HWPI exhibits the highest magnitude of ionic and hydrophobic interactions.