title: Variable region identical immunoglobulins differing in isotype express different paratopes.
abstract: The finding that the antibody (Ab) constant (C) region can influence fine specificity suggests that isotype switching contributes to the generation of Ab diversity and idiotype restriction. Despite the centrality of this observation for diverse immunological effects such as vaccine responses, isotype-restricted antibody responses, and the origin of primary and secondary responses, the molecular mechanism(s) responsible for this phenomenon are not understood. In this study, we have taken a novel approach to the problem by probing the paratope with (15)N label peptide mimetics followed by NMR spectroscopy and fluorescence emission spectroscopy. Specifically, we have explored the hypothesis that the C region imposes conformational constraints on the variable (V) region to affect paratope structure in a V region identical IgG(1), IgG(2a), IgG(2b), and IgG(3) mAbs. The results reveal isotype-related differences in fluorescence emission spectroscopy and temperature-related differences in binding and cleavage of a peptide mimetic. We conclude that the C region can modify the V region structure to alter the Ab paratope, thus providing an explanation for how isotype can affect Ab specificity.
authors.affiliation: Department of Microbiology and Immunology, The Albert Einstein College of Medicine, Bronx, New York 10461.
authors.forename: Alena
authors.initials: A
authors.lastname: Janda
authors.affiliation: Department of Biochemistry, The Albert Einstein College of Medicine, Bronx, New York 10461.
authors.forename: Ertan
authors.initials: E
authors.lastname: Eryilmaz
authors.affiliation: Department of Microbiology and Immunology, The Albert Einstein College of Medicine, Bronx, New York 10461.
authors.forename: Antonio
authors.initials: A
authors.lastname: Nakouzi
authors.affiliation: Department of Biochemistry, The Albert Einstein College of Medicine, Bronx, New York 10461.
authors.forename: David
authors.initials: D
authors.lastname: Cowburn
authors.affiliation: Department of Microbiology and Immunology, The Albert Einstein College of Medicine, Bronx, New York 10461; Division of Infectious Diseases, Department of Medicine, The Albert Einstein College of Medicine, Bronx, New York 10461. Electronic address: arturo.casadevall@einstein.yu.edu.
authors.forename: Arturo
authors.initials: A
authors.lastname: Casadevall
mesh_terms: D000818:Animals; D058846:Antibodies, Monoclonal, Murine-Derived / Q000096:biosynthesis* / Q000235:genetics; D000918:Antibody Specificity / Q000502:physiology*; D001666:Binding Sites, Antibody / Q000502:physiology*; D007127:Immunoglobulin Constant Regions / Q000096:biosynthesis / Q000235:genetics; D007074:Immunoglobulin G / Q000096:biosynthesis* / Q000235:genetics; D007135:Immunoglobulin Variable Region / Q000096:biosynthesis* / Q000235:genetics; D051379:Mice
chemical_list: D058846:Antibodies, Monoclonal, Murine-Derived; D007127:Immunoglobulin Constant Regions; D007074:Immunoglobulin G; D007135:Immunoglobulin Variable Region