Characterizing monoclonal antibody structure by carbodiimide/GEE footprinting

Area of Science:

• Biochemistry
• Structural Biology
• Drug Development

Background:

• Amino acid-specific covalent labeling is crucial for studying complex macromolecules.
• Monoclonal antibody therapeutics are vital biologic drugs requiring precise characterization.
• Understanding protein structure and interactions is essential for developing new medicines.

Purpose of the Study:

• To detail carbodiimide-based covalent labeling (GEE tagging) for glycosylated monoclonal antibodies.
• To optimize labeling experiments for protein structural integrity and assess reproducibility.
• To correlate experimental surface accessibility with homology model predictions for unbiased structural assessment.

Main Methods:

• Carbodiimide-based covalent labeling with GEE tagging was applied to a glycosylated monoclonal antibody.
• Experiments were optimized and replicated to ensure structural integrity and assess reproducibility.
• Homology modeling was used to predict solvent accessibility and compare with experimental data.

Main Results:

• The carbodiimide/GEE labeling method is easy to use, reproducible (<2% variation), and provides linear dose-response plots.
• Labeled residues (D, E, C-terminus) showed significant correlation between reactivity and predicted solvent accessible surface area.
• Reactivity was attenuated by local charge or bond formation, providing insights into sequence/structure-based variations.

Conclusions:

• Carbodiimide-based covalent labeling is an accurate and precise method for assessing the structure of biologic drugs.
• The technique offers complementary information to other methods like hydroxyl radical footprinting.
• This approach aids in the development of new biologic-based medicines by providing reliable structural data.