Open AccessThree-dimensional structure of two crystal forms of FabR19.9 from a monoclonal anti-arsonate antibody.
Author(s) -
Marie-Bernard Lascombe,
Pedro M. Alzari,
Roberto J. Poljak,
Alfred Nisonoff
Publication year - 1992
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.89.20.9429
Subject(s) - hapten , chemistry , metastability , complementarity determining region , crystallography , complementarity (molecular biology) , monoclonal antibody , stereochemistry , molecular replacement , protein tertiary structure , crystal structure , intermolecular force , antibody , molecule , biology , biochemistry , immunology , genetics , organic chemistry
The three-dimensional structure of FabR19.9 from a well-characterized anti-p-azobenzenearsonate monoclonal antibody has been determined by x-ray diffraction techniques in two crystalline forms (I and II) to a resolution of 2.8 and 2.7 A, respectively. Essentially the same tertiary and quaternary structure of the Fab is observed in the two forms. The major difference resides in the intermolecular contacts, which are interpreted to favor an irreversible transition from the metastable form I to the more stable form II. The third complementarity-determining region of the heavy chain (H3) folds back over the combining site and requires rearrangement for hapten binding. This dynamic requirement on H3 is consistent with its mobility in the structure and can explain hapten binding to an otherwise inaccessible antibody combining site.