Monoclonal antibodies (MAbs) of the immunoglobulin G (IgG) type are an important class of therapeutic glycoproteins. Compelling evidence has indicated that the fine structures of the glycans at the conserved N-glycosylation site (Asn-297) of the Fc domain are responsible for the distinct effector functions of MAbs, including antibody-dependent cellular cytotoxicity (ADCC), complement-dependent cytotoxicity (CDC), and activation of apoptosis. In addition, a special sialylated Fc glycoform was identified to be responsible for the antiinflammatory activity of intravenous immunoglobulin (IVIG). However, progress in understanding the functional roles of IgG-Fc glycosylation is hampered by the tremendous structural heterogeneity of Fc domain glycans. In addition, controlling glycosylation of MAbs in expression to a desired homogeneous glycoform is still a challenging task. In this application, we propose to explore a chemoenzymatic method to make a library of homogeneously glycosylated IgG-Fc and selected glycoforms of MAbs. Through performing Fc receptor binding studies, we aim to understand how different glycan structures can fine tune the effector functions of IgG and IgG-Fc protein. We have performed important preliminary studies indicating that it is feasible to use the endoglycosidase-based transglycosylation approach to construct defined, homogeneous glycoforms of human IgG-Fc. Building on this success, we propose to pursue three specific aims.
Aim 1 is to explore a chemoenzymatic method for the construction of various pure glycoforms of IgG-Fc.
Aim 2 is to evaluate the structure-activity realtionships of different Fc domain glycoforms in Fc receptor binding, and to evaluate ADCC activity of selectively glycoengineered monoclonal antibodies.
Aim 3 is to synthesize novel Fc domain glycoforms for evaluating the roles of IgG-Fc glycosylation in anti-inflammatory activity. The knowledge gained from the proposed research will eventually facilitate the development of novel glycoforms of MAbs and IgG-Fc proteins as effective therapeutics.

Public Health Relevance

IgG antibodies are an important class of therapeutic glycoproteins. The Fc domain glycosylation is essential for antibody's effector functions including ADCC and anti-inflammatory activity. The proposed research aims to decipher the functional roles of Fc glycosylation through glycosylation engineering and Fc receptor binding studies; which may lead to the discovery of novel antibody glycoforms with potent therapeutic efficacy.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
Project #
Application #
Study Section
Special Emphasis Panel (ZRG1-BCMB-B (03))
Program Officer
Marino, Pamela
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of Maryland College Park
Schools of Earth Sciences/Natur
College Park
United States
Zip Code
Li, Tiezheng; Li, Chao; Quan, David N et al. (2018) Site-specific immobilization of endoglycosidases for streamlined chemoenzymatic glycan remodeling of antibodies. Carbohydr Res 458-459:77-84
Giddens, John P; Lomino, Joseph V; DiLillo, David J et al. (2018) Site-selective chemoenzymatic glycoengineering of Fab and Fc glycans of a therapeutic antibody. Proc Natl Acad Sci U S A 115:12023-12027
Li, Chao; Wang, Lai-Xi (2018) Chemoenzymatic Methods for the Synthesis of Glycoproteins. Chem Rev 118:8359-8413
Bennett, Lindsay D; Yang, Qiang; Berquist, Brian R et al. (2018) Implementation of Glycan Remodeling to Plant-Made Therapeutic Antibodies. Int J Mol Sci 19:
Tong, Xin; Li, Tiezheng; Orwenyo, Jared et al. (2018) One-pot enzymatic glycan remodeling of a therapeutic monoclonal antibody by endoglycosidase S (Endo-S) from Streptococcus pyogenes. Bioorg Med Chem 26:1347-1355
Li, Chao; Li, Tiezheng; Wang, Lai-Xi (2018) Chemoenzymatic Defucosylation of Therapeutic Antibodies for Enhanced Effector Functions Using Bacterial ?-Fucosidases. Methods Mol Biol 1827:367-380
Tong, Xin; Li, Tiezheng; Li, Chao et al. (2018) Generation and Comparative Kinetic Analysis of New Glycosynthase Mutants from Streptococcus pyogenes Endoglycosidases for Antibody Glycoengineering. Biochemistry 57:5239-5246
Li, Tiezheng; DiLillo, David J; Bournazos, Stylianos et al. (2017) Modulating IgG effector function by Fc glycan engineering. Proc Natl Acad Sci U S A 114:3485-3490
Yang, Qiang; Wang, Lai-Xi (2017) Chemoenzymatic Glycan Remodeling of Natural and Recombinant Glycoproteins. Methods Enzymol 597:265-281
Li, Chao; Zhu, Shilei; Ma, Christopher et al. (2017) Designer ?1,6-Fucosidase Mutants Enable Direct Core Fucosylation of Intact N-Glycopeptides and N-Glycoproteins. J Am Chem Soc 139:15074-15087

Showing the most recent 10 out of 23 publications