Isothermal titration calorimetry reveals differential binding thermodynamics of variable region-identical antibodies differing in constant region for a univalent ligand

Tarun K. Dam, Marcela Torres, Curtis F. Brewer, Arturo Casadevall

Research output: Contribution to journalArticle

39 Citations (Scopus)

Abstract

The classical view of immunoglobulin molecules posits two functional domains defined by the variable (V) and constant (C) regions, which are responsible for antigen binding and antibody effector functions, respectively. These two domains are thought to function independently. However, several lines of evidence strongly suggest that C region domains can affect the specificity and affinity of an antibody for its antigen (Ag), independent of avidity-type effects. In this study, we used isothermal titration calorimetry to investigate the thermodynamic properties of the interactions of four V region-identical monoclonal antibodies with a univalent peptide antigen. Comparison of the binding of IgG1, IgG2a, IgG2b, and IgG3 with a 12-mer peptide mimetic of Cryptococcus neoformans polysaccharide revealed a stoichiometry of 1.9-2.0 with significant differences in thermodynamic binding parameters. Binding of this peptide to the antibodies was dominated by favorable entropy. The interaction of these antibodies with biotinylated peptides manifested greater enthalpy than for native peptides indicating that biotin labeling affected the types of Ag-Ab complexes formed. Our results provide unambiguous thermodynamic evidence for the notion that the C region can affect the interaction of theVregion with an Ag.

Original languageEnglish (US)
Pages (from-to)31366-31370
Number of pages5
JournalJournal of Biological Chemistry
Volume283
Issue number46
DOIs
StatePublished - Nov 14 2008

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Calorimetry
Titration
Thermodynamics
Ligands
Antigens
Peptides
Antibodies
Immunoglobulin G
Cryptococcus neoformans
Antibody Affinity
Antibody Specificity
Entropy
Biotin
Stoichiometry
Labeling
Polysaccharides
Immunoglobulins
Enthalpy
Thermodynamic properties
Monoclonal Antibodies

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology
  • Molecular Biology

Cite this

Isothermal titration calorimetry reveals differential binding thermodynamics of variable region-identical antibodies differing in constant region for a univalent ligand. / Dam, Tarun K.; Torres, Marcela; Brewer, Curtis F.; Casadevall, Arturo.

In: Journal of Biological Chemistry, Vol. 283, No. 46, 14.11.2008, p. 31366-31370.

Research output: Contribution to journalArticle

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