Glycoengineering and glycosite-specific labeling of serum IgGs from various species.

Chemoenzymatic glycoengineering of immunoglobulin G (IgG) catalyzed by Endo-S is a powerful approach to remodel the heterogeneous N-glycoforms of Fc domain with a homogeneous synthetic glycan structure for enhanced Fc receptor-mediated effector functions. The previous researches on the method development mainly focused on human or humanized IgGs with therapeutic potentials. Here, for the first time we report the extended application of this method on glycan-remodeling of serum IgGs from other species including rabbit, mouse, and goat. Harnessing an azido-tagged non-natural N-glycan substrate and successive click reaction, glycosite-specific fluorescent labeling of IgGs was enabled. This study provided a new avenue for glycoengineering and Fc-specific labeling of IgGs with minimized influence on antigen-binding domains, and this method was adaptive to thousands of commercial antibody reagents from various species with great application potentials.