Flexibility of an antibody binding site measured with photon echo spectroscopy

Ralph Jimenez, David A. Case, Floyd E. Romesberg

Research output: Contribution to journalArticlepeer-review

45 Scopus citations


The lock-and-key and induced fit models of antigen binding by antibodies are topics of considerable importance to immunology and protein biochemistry in general. These models ascribe different degrees of flexibility to the antibody combining site and may therefore be distinguished by measuring the response of the protein to the force exerted by charge redistribution and structural reorganization of an optically excited antigen. Spectroscopic characterization of the magnitude and time scale of this protein reorganization is therefore a basis for comparing the flexibility of different antibodies. This approach is used to study a panel of antibodies elicited to the chromophoric antigen 8-methoxypyrene-1,3,6,trisulfonic acid. The reorganization energies of the chromophore-antibody complexes are determined and are found to be distributed over a wide range. Three pulse photon echo peak shift spectroscopy is used to measure the time scales of the reorganization process in one complex. The antibody motions occur on time scales ranging from 75 femtoseconds to 67 picoseconds. Structural origins of the observed protein motions are discussed.

Original languageEnglish (US)
Pages (from-to)1090-1103
Number of pages14
JournalJournal of Physical Chemistry B
Issue number5
StatePublished - Feb 7 2002
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry


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