多光谱法探究壳聚糖与酪蛋白的结合作用

目的 以壳聚糖(Chitosan,CS)和酪蛋白(Casein,CA)为研究对象,通过探究多糖对蛋白质结构的影响机制,以期改进多糖对蛋白质食品贮藏的效果。方法 采用荧光光谱法和傅里叶变换红外光谱法,在不同pH条件下,研究CS与CA的结合反应,通过数学方程计算其结合常数、结合位点数和结合作用力。结果 不同pH值条件下,CS对CA均产生荧光猝灭,均属于静态猝灭,pH=5.2时猝灭常数达到最大值4.702×10³ L/mol,且结合常数达到最大值9.914×10³ L/mol。热力学分析表明,结合反应自发进行属于放热反应,主要结合驱动力为静电相互作用。同步荧光光谱和三维荧光光谱表明,CS与CA的相互作用能够使CA的空间构象发生改变。傅里叶变换红外光谱说明CS加入和pH值的变化导致了CA二级结构发生变化。结论 CS与CA结合会导致CA的结构发生变化,这为蛋白质–多糖相互作用提供一定的理论依据,也为以蛋白质–多糖为基础的乳制品贮藏及开发提供实验依据。

Binding Behavior between Chitosan and Casein by Multi-spectroscopic Method

The work aims to improve the effect of polysaccharide on protein food storage by exploring the affecting mechanism of polysaccharide on protein structure with chitosan and casein as research objects. Fluorescence spectroscopy and Fourier transform infrared spectroscopy were used to study the binding reaction between chitosan and casein under different pH conditions, and the binding constant, number of binding sites and binding force were calculated by mathematical equations. Under different pH conditions, chitosan quenched the fluorescence of casein, which belonged to static quenching. The quenching constant reached the maximum value of 4.702×103 L/mol at pH=5.2, and the binding constant reached the maximum value of 9.914×103 L/mol. Thermodynamic analysis showed that the spontaneous binding reaction was an exothermic reaction, and the main binding driving force was electrostatic interaction. Synchronous fluorescence spectroscopy and three-dimensional fluorescence spectroscopy indicated that the interaction of chitosan and casein could change the spatial conformation of casein. Fourier transform infrared spectroscopy illustrated that the addition of chitosan and the change of pH led to changes in the secondary structure of casein. The combination of chitosan and casein leads to structural changes in casein, which provides some theoretical basis for protein-polysaccharide interactions and also provides some experimental basis for the storage and development of dairy products based on protein-polysaccharide.