花青素对大豆蛋白质二级结构影响的多重光谱分析

以大豆分离蛋白-花青素复合体系为研究对象,综合利用多重光谱技术对其进行分析。利用荧光光谱探究大豆分离蛋白和花青素间的相互作用方式,采用同步荧光光谱和紫外-可见光谱探究花青素对大豆分离蛋白氨基酸残基微环境的影响,从而得出花青素对大豆分离蛋白构象的影响,再采用傅里叶变换红外光谱法和圆二色谱法研究花青素对大豆分离蛋白二级结构的影响。结果表明:花青素对大豆分离蛋白有较强的荧光猝灭作用且为静态猝灭,其中,花青素与大豆分离蛋白在298、306、314 K时相互作用的表观结合常数分别为3.343×104、4.507×104、5.525×104L/mol,对应的结合位点数分别为0.917 8、0.954 6、0.938 1。热力学数据分析结果表明:花青素与大豆分离蛋白反应的作用力主要是疏水相互作用;同步荧光光谱和紫外-可见光谱结果表明花青素改变了芳香氨基酸残基在空间结构中所处的微环境,使大豆分离蛋白的分子构象发生改变,且同步荧光光谱显示花青素与大豆分离蛋白中色氨酸残基发生相互作用,使其周围的疏水作用减少。傅里叶变换红外光谱和圆二色谱结果表明花青素引起大豆分离蛋白的二级结构发生改变。

Effects of Anthocyanins on the Secondary Structure of Soybean Protein Isolate by Multiplex Spectroscopy

Soybean protein isolate-anthocyanin complex system was used as the object of study. The interaction between soybean protein and anthocyanin was explored by fluorescence spectroscopy, UV-Vis spectroscopy, Fourier transform infrared spectroscopy and circular dichroism. The effect of anthocyanins on the structure of soybean protein isolate was studied by Fourier transform infrared spectroscopy and circular dichroism. The effect of anthocyanin on the structure of soybean protein isolate was studied by Fourier transform infrared spectroscopy and circular dichroism. The results showed that anthocyanin had strong fluorescence quenching effect on soybean protein isolate in a static mode. The apparent binding constants of anthocyanin and soybean protein isolate at 298K, 306K and 314K were 3.343×104L/mol, 4.507×104L/mol and 5.525×104L/mol, the corresponding binding sites were 0.9178, 0.9546 and 0.9381, respectively. The results of thermodynamic data showed that the interaction between anthocyanin and soybean protein isolate was mainly hydrophobic interaction. Synchronous fluorescence spectroscopy and UV-Vis spectra showed that anthocyanins changed the microenvironment of aromatic amino acid residues in the spatial structure and the conformation of soy protein isolate, and the synchronous fluorescence spectrum showed that the anthocyanin interacted with the tryptophan residue in the soybean protein isolate and reduced the hydrophobic interaction. Fourier transform infrared spectroscopy and circular dichroism showed that the secondary structure of soybean protein was changed by anthocyanin.