Abstract：
Glycosylation is a method that enhances the functional properties of proteins by covalently attaching sugars to them. This study aimed at preparing three conjugates (WP-HG, WP-SBP, and WP-RGI) by dry heating method to research the influence of different pectin structures on the functional properties of WP and characterize properties and structures of these conjugates. The research results manifested that the degree of glycosylation (DG) of HG, SBP and RGI were 13.13 % ± 0.07 %, 23.27 % ± 0.3 % and 36.39 % ± 0.3 % respectively, suggesting that the increase of the number of branch chains promoted the glycosylation reaction. The formation of the conjugate was identified by the FT-IR spectroscopy technique. And SEM showed that WP could covalently bind to pectin, resulting in a smoother and denser surface of the conjugates. The circular dichroism analysis exhibited that the glycosylation reaction altered the secondary structure of WP and decreased the α-Helix content. This structural change in the protein spatial conformation led to a decrease in the hydrophobicity of protein surface. But the addition of pectin further regulated the hydrophilic-hydrophobic ratio on the surface of the protein, thus improving the emulsification properties of WP. In addition, the glycosylation could improve the stability of the emulsion, giving it a smaller droplet size, higher Zeta-potential and more stable properties. In a word, this study pointed out the direction for the application of different pectin structures in the development of functional properties of glycosylation products in food ingredients.
摘要：
糖基化是一种通过将糖共价连接到蛋白质上来增强蛋白质功能特性的方法。本研究旨在制备三种偶联物（WP-HG，WP-SBP,和WP-RGI）通过干热方法研究了不同果胶结构对WP功能性质的影响，并表征了这些缀合物的性质和结构。研究结果表明,HG的糖基化程度(DG),SBP和RGI为13.13%±0.07%,分别为23.27%±0.3%和36.39%±0.3%，表明支链数量的增加促进了糖基化反应。通过FT-IR光谱技术鉴定缀合物的形成。SEM显示WP可以共价结合果胶，导致缀合物的更光滑和更致密的表面。圆二色性分析表明，糖基化反应改变了WP的二级结构，降低了α-螺旋含量。蛋白质空间构象的这种结构变化导致蛋白质表面疏水性降低。但果胶的加入进一步调节了蛋白质表面的亲水疏水比,从而提高WP的乳化性能。此外,糖基化可以提高乳液的稳定性,给它更小的液滴尺寸，更高的Zeta电位和更稳定的性能。一句话,本研究为不同结构的果胶在食品原料糖基化产品功能特性开发中的应用指明了方向。
