糖基化修饰对油茶油脂体界面结构及稳定性的影响Effect of glycosylation on interfacial structure and stabilities of oil body extracted from Camellia oleifera seed

油脂体是植物种子储油细胞器，由单层磷脂与界面蛋白共同稳定。为增加油脂体的pH稳定性，选用葡萄糖和乳糖为羰基供体，通过糖基化修饰油茶油脂体的界面结构。通过粒径及Zeta-电位的变化综合评估油脂体物理稳定性，采用聚丙烯酰胺凝胶电泳考察油脂体膜蛋白分子质量变化，采用Thermo Scientific Pierce BCA试剂盒分析油脂体膜蛋白溶解度的变化，并利用拉曼共聚焦显微镜观察油脂体界面结构的变化。结果表明：糖基化反应增大了油茶油脂体粒径，但粒径分布更均一，而Zeta-电位未发生显著变化（p>0.05）；葡萄糖和乳糖与油脂体质量比分别为2∶ 1和5∶ 1时糖基化油脂体膜蛋白溶解度最高，分别比对照组（未糖基化油脂体）提升了26.8倍和16.1倍。糖基化后油脂体膜蛋白分子质量小幅增大；拉曼光谱分析表明糖与油脂体膜蛋白成功接枝。综上，糖基化有利于提高油茶油脂体稳定性。Oil body is the oil storage organelle in oilseeds, which is stabilized by a monolayer of phospholipids and membrane proteins. In order to increase the pH stability of oil body, glucose and lactose were used as carbonyl donors to modify the interfacial structure of oil bodies (OBs) extracted from Camellia oleifera seed via glycosylation. The physical stabilities of OBs were evaluated via particle size and Zeta-potential. The molecular weight and solubility of OBs membrane protein were investigated by sodium dodecyl sulfate polyacrylamide gel electrophoresis and Thermo Scientific Pierce BCA kit, respectively. The interfacial structure of OBs was observed by Raman-confocal microscope. The results showed that the glycosylation reaction increased the particle size of Camellia oleifera OBs, but the particle size became more uniform, and the Zeta-potential did not change significantly (p>0.05). Under the conditions of mass ratio of glucose to OBs 2∶ 1, and mass ratio of lactose to OBs 5∶ 1, the glycosylated OBs membrane protein exhibited the highest solubility, with increase of 26.8 times and 16.1 times compared with the control (unglycosylation), respectively. The molecular weight of OBs membrane protein increased slightly after glycosylation. Raman spectra analysis showed that the glucose and lactose were successfully grafted on membrane proteins of OBs. In conclusion, glycosylation is beneficial for improving the stability of OBs.