卵白蛋白-壳聚糖静电相互作用对蛋白质结构和热特性的影响

明确蛋白质与多糖之间静电相互作用对蛋白质结构和热特性的影响，可为深入理解两者静电复合物界面特性机制提供新见解。基于此，本研究借助紫外可见光谱、内源荧光光谱、圆二色谱、傅里叶变换光谱和差示扫描量热仪探究卵白蛋白（Ovalbumin，OVA）与壳聚糖（Chitosan，CS）之间的静电相互作用对OVA二级、三级结构及热特性的影响。结果表明，静电排斥力和静电吸引力都会导致OVA的结构发生去折叠，主要表现为色氨酸残基向亲水区域迁移且暴露程度下降；α-螺旋、β-转角和自由卷曲含量分别下降约26.9%、52.3%、6.0%，β-折叠增加约33.9%。此外，OVA的热变性温度也由于静电结合作用由78 ℃上升至83 ℃。这些发现可为利用多糖通过静电作用调控OVA功能特性提供参考和思路借鉴。

Electrostatic Interaction of Ovalbumin-Chitosan on the Effects of Protein Structure and Thermal Properties

Understanding the effect of electrostatic interaction between protein and polysaccharide on the structure and thermal properties of protein could provide new insights into the mechanism of interfacial properties of electrostatic complexes. Herein, the effects of electrostatic interaction between ovalbumin(OVA) and chitosan(CS) on the secondary, tertiary structure and thermal properties of OVA were investigated by UV-vis spectroscopy, intrinsic fluorescence spectroscopy, circular dichroism, Fourier transform spectroscopy and differential scanning calorimetry. The results showed that both electrostatic repulsion and electrostatic attraction could cause the structure of OVA to unfold, which was mainly characterized by the migration of tryptophan residues to the hydrophilic region and the decrease of exposure degree. The contents of α-helix, β-turn and random coil decreased by 26.9%, 52.3% and 6.0%, respectively, and the β-sheet increased by 33.9%. In addition, the thermal denaturation temperature of OVA increased from 78 ℃ to 83 ℃ due to electrostatic binding. These findings could provide a reference for the use of polysaccharides to regulate the functional properties of OVA through electrostatic interaction.