细胞表面糖链标记方法广泛应用于蛋白糖基化功能的可视化研究。然而由于N-糖基化的复杂结构，针对精确N-糖型的选择性标记方面仍然面临困境，缺乏有效的系统的技术手段，是该领域亟待攻克的难题和瓶颈。我们在前期工作中，建立了Endo酶催化高效合成各种均一N-糖型结构的糖蛋白方法，同时利用Endo酶家族的底物识别特异性，区分细胞表面N-糖链亚型，成功地实现了细胞N-糖链的亚型选择性调控与标记，并进行了细胞成像研究。进一步地，我们设计了基于特定蛋白和特定糖链的高选择性FRET标记技术，实现蛋白糖基化功能的精确分子机制可视化研究。本课题运用化学-酶催化方法，选择性调控和标记细胞表面N-糖链，建立和发展新颖的、系统的选择性标记方法，探索细胞表面特定蛋白（如药物受体）上精确糖型介导的生物学功能，解决复杂N-糖链结构阻碍精确分子机制解析的技术瓶颈，促进与疾病相关的化学糖生物学发展。

Cell surface glycan labeling is a powerful tool widely used in visualizable investigation on protein glycosylation functions. However, the precise N-glycan selective labeling is still a challenging task because of the complexity of N-glycosylation structures. Lack of effective and systematic approach of selective labeling is the key bottleneck in this field. In our previous work, we established the efficient chemoenzymatic method to synthesize homogeneous glycoproteins with various well-defined glycans. Meanwhile, we successfully applied this technique in cell surface N-glycan selective labeling for cell imaging by using Endo-glycosidase family to distinguish the cell-surface N-glycan subtypes by their substrate specificity. Moreover, we sought to develop the high selective FRET technology to label the specific N-glycan subtype of the particular glycoprotein for visualizable studies on molecular mechanism of glycosylation bio-function. In current project, we intend to employ the chemoenzymatic method to selectively manipulate and label the cell surface N-glycans therefore establish and develop a novel and systematic labeling strategy for exploring the glycosylation-mediated biological functions of specific proteins such as drug receptors in cell surface. This work provided a solution to overcome the technique bottleneck in the precise elucidation on glycosylation-involved molecular mechanism that was hampered by the complicated N-glycan structures, hence it will benefit the disease-related researches in chemical glycobiology.