单宁酸与大豆分离蛋白相互作用研究

Interaction between tannic acid and soy protein isolate

利用荧光光谱、紫外光谱和圆二色谱,从分子水平研究单宁酸与大豆分离蛋白的相互作用。结果表明:单宁酸对大豆分离蛋白有较强的荧光猝灭作用,当单宁酸浓度小于6×10^-6mol/L(相对于大豆分离蛋白质量分数5.1%)时,猝灭类型为静态猝灭,当单宁酸浓度大于6×10^-6mol/L时,同时存在静态猝灭和动态猝灭;单宁酸通过疏水作用与大豆分离蛋白结合,导致大豆分离蛋白的色氨酸和酪氨酸残基微环境亲水性增强,但对大豆分离蛋白的二级结构没有显著影响。

The interaction between tannic acid and soy protein isolate was examined at a molecular level by the means of fluorescence,ultraviolet-visible and circular dichroism spectra.The results suggested that tannic acid had a strong ability to quench the intrinsic fluorescence of soy protein isolate.When the concentration of tannic acid was below 6×10^-6 mol/L(mass fraction 5.1%based on soy protein isolate),the quenching mechanism was mainly a static quenching.In contrast,when the concentration of tannic acid was above 6×10^-6 mol/L,the quenching mechanism included both static and dynamic quenching.Hydrophobic force played a major role in the binding of tannic acid and soy protein isolate,and led the microenvironment of tryptophan and tyrosine residues of soy protein isolate more hydrophilic,but had no significant effect on the secondary structures of soy protein isolate.