Mechanical stability of the antibody domain CH3 homodimer in different oxidation states

Morten Bertz, Johannes Buchner, Matthias Rief

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

The CH3 homodimer at the C-terminal end of the antibody heavy chain is the key noncovalent interaction stabilizing antibody proteins. Here, we use single-molecule force spectroscopy to investigate the dissociation mechanics of CH3 as a proxy for antibody mechanical stability. We find the CH3 homodimer to be a highly stable complex, and its dissociation force of >150 pN at a loading rate of ≈5500 pN/s exceeds the stability of most protein-protein interactions studied to date. Separated C H3 monomers, on the other hand, are mechanically labile and only short-lived. Each CH3 monomer contains a conserved buried disulfide bridge, and we find that the successive reduction of one or both disulfide bridges in the dimer results in a stepwise decrease of the dissociation force. This suggests a structural role of the disulfide bridges helping to mold the high-affinity domain-domain interface, even though they are neither required for nor directly involved in dimerization. Taken together, our results set a limit on how much force a single antibody can bear and reveal the CH3 homodimer as a mechanical fastener that prevents antibody dissociation.

Original languageEnglish
Pages (from-to)15085-15091
Number of pages7
JournalJournal of the American Chemical Society
Volume135
Issue number40
DOIs
Publication statusPublished - 2013 Oct 21

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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