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Updated: Aug 6, 2026
07:39
Determining Binding Affinity (KD) of Radiolabeled Antibodies to Immobilized Antigens
Published on: June 23, 2022
Long-range allosteric communication within antibodies affects antigen-binding affinity
Susan K Vester1, Brian J Sutton1, James M McDonnell1
1Randall Centre for Cell and Molecular Biophysics, King's College London, New Hunt's House, London, United Kingdom.
Frontiers in Immunology
|July 23, 2026
Summary
Antibody allosteric communication, influenced by Fc regions, significantly impacts antigen-binding affinity. Understanding these long-range effects is crucial for antibody engineering and therapeutic development.
Area of Science:
- Immunology
- Structural Biology
- Biochemistry
Background:
- Antibodies are key immune molecules with antigen recognition and effector functions.
- Allosteric communication within antibodies and its impact on antigen-binding affinity, especially isotype-dependent effects, are poorly understood.
Purpose of the Study:
- To comprehensively compare allosteric effects on antigen-binding affinities across different antibody isotypes (IgA1, IgD, IgE, IgG1, IgG4, IgM).
- To investigate the influence of the Fc region and C_H1 domain on antibody-antigen interactions.
Main Methods:
- Surface plasmon resonance (SPR) was used to compare binding affinities of various antibody fragments (Fabs) and full-length antibodies across five antigen systems.
- Thermodynamic analysis was employed to understand the drivers of observed affinity differences.
Main Results:
- While C_H1 domains showed minor allosteric affinity differences, the Fc region exerted significant long-range allosteric effects on Fab binding.
- Full-length antibodies demonstrated higher binding affinities than their Fab counterparts, irrespective of avidity.
- Differences in antibody flexibility and pre-organization were identified as key thermodynamic drivers.
Conclusions:
- Allosteric modulation, involving the C_H1 domain, Fc region, and Fc-ligand interactions, critically determines antibody function.
- These findings provide essential insights for evaluating and engineering antibody-based therapeutics.
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