First site-specific conjugation method for native goat IgG antibodies via glycan remodeling at the conserved Fc region

Michael E Dolan; Amissi Sadiki; Leo Lei Wang; Yan Wang; Christopher Barton; Sheldon F Oppenheim; Zhaohui Sunny Zhou

doi:10.1093/abt/tbae014

First site-specific conjugation method for native goat IgG antibodies via glycan remodeling at the conserved Fc region

Antib Ther. 2024 Jul 10;7(3):233-248. doi: 10.1093/abt/tbae014. eCollection 2024 Jul.

Authors

Michael E Dolan^{1

2

3}, Amissi Sadiki^{1

2}, Leo Lei Wang⁴, Yan Wang⁴, Christopher Barton⁴, Sheldon F Oppenheim³, Zhaohui Sunny Zhou^{1

2}

Affiliations

¹ Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA 02115, United States.
² Barnett Institute of Chemical and Biological Analysis, Northeastern University, Boston, MA 02115, United States.
³ Biotherapeutics Process Development, Takeda Development Center Americas, 200 Shire Way, Lexington, MA 02421, United States.
⁴ Analytical Development, Takeda Development Center Americas, 200 Shire Way, Lexington, MA 02421, United States.

PMID: 39262442
PMCID: PMC11384149 (available on 2025-07-10)
DOI: 10.1093/abt/tbae014

Abstract

Despite their triumph in treating human diseases, antibody therapies for animals have gained momentum more slowly. However, the first approvals of animal antibodies for osteoarthritic pain in cats and dogs may herald the dawn of a new era. For example, goats are vital to economies around the world for their milk, meat, and hide products. It is therefore imperative to develop therapies to safeguard goats-with antibodies at the forefront. Goat antibodies will be crucial in the development of therapeutic antibodies, for example, as tracers to study antibody distribution in vivo, reagents to develop other therapeutic antibodies, and therapeutic agents themselves (e.g., antibody-drug conjugates). Hamstringing this effort is a still-burgeoning understanding of goat antibodies and their derivatization. Historically, goat antibody conjugates were generated through stochastic chemical modifications, producing numerous attachment sites and modification ratios, thereby deleteriously impacting antigen binding. Site-specific methods exist but often require substantial engineering and have not been demonstrated with goat antibodies. Nevertheless, we present herein a novel method to site-specifically conjugate native goat antibodies: chemo-enzymatic remodeling of the native Fc N-glycan introduces a reactive azide handle, after which click chemistry with strained alkyne partners affords homogeneous conjugates labeled only on the Fc domain. This process is robust, and resulting conjugates retain their antigen binding and specificity. To our knowledge, our report is the first for site-specific conjugation of native goat antibodies. Furthermore, our approach should be applicable to other animal antibodies-even with limited structural information-with similar success.

Keywords: AntibodyPlus; glycan remodeling; glycan-mediated conjugation; goat antibody; green fluorescent protein (GFP); phospholipase B-like 2 (PLBL2); site-specific conjugation.