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Conformational isomerism of IgG antibodies

Author

  • Ulla-Britt Hansson
  • Christer Wingren
  • Ulf Alkner

Summary, in English

The purpose of this study was to determine why apparently homogeneous IgG antibodies were, in some cases, fractionated into at least two components by liquid-liquid partition chromatography (LLPC) in an aqueous two-phase system. Four mouse monoclonal IgG antibodies, two against albumin, one against IgG and one against thyroxine, were shown to adopt different conformational isomeric forms. The four antibodies existed in an equilibrium between two or three conformational forms, the proportion of which could also be estimated by LLPC. Since LLPC detects mainly conformational differences within the antigen-binding sites of IgG antibodies, it could be concluded that the conformational forms differed with respect to their combining sites. Moreover, the isomeric forms of an antibody directed against a protein antigen, formed antigen-antibody complexes with almost identical surface properties. In contrast, complexes with different surface properties were formed when the hapten or hapten conjugated to BSA was bound. Thus, both the conformational isomers could bind antigen, at least when the antigen was a small hapten or a hapten conjugated to a carrier protein. Our results suggest that six out of 57 monoclonal IgG antibodies exist in equilibrium between at least two conformational forms and the biological significance of this isomerism is discussed.

Publishing year

1997

Language

English

Pages

53-62

Publication/Series

BBA - Protein Structure and Molecular Enzymology

Volume

1340

Issue

1

Document type

Journal article

Publisher

Elsevier

Topic

  • Biological Sciences

Keywords

  • Antigen binding
  • Conformational isomerism
  • IgG antibody
  • Phase partition
  • Liquid-liquid partition chromatography
  • Surface property

Status

Published

ISBN/ISSN/Other

  • ISSN: 0167-4838