8fab
CRYSTAL STRUCTURE OF THE FAB FRAGMENT FROM THE HUMAN MYELOMA IMMUNOGLOBULIN IGG HIL AT 1.8 ANGSTROMS RESOLUTION
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OverviewOverview
The structure of the antigen-binding fragment (Fab) of an, anti-p-azophenylarsonate monoclonal antibody, 36-71, bearing a major, cross-reactive idiotype of A/J mice has been refined to an R factor of, 24.8% at a resolution of 1.85 A. The previously solved partial structure, of this Fab at a resolution of 2.9 A (Rose et al., 1990) was used as an, initial model for refinement against the high-resolution data. The complex, with hapten has been modeled by docking the small-molecule crystal, structure of phenylarsonic acid into the structure of the native Fab on, the basis of a low-resolution electron density map of the complex. In this, model, residue Arg-96 in the light chain and residues Asn-35, Trp-47, and, Ser-99 in the heavy chain contact the arsonate moiety of the hapten; an, additional bond is found between the arsonate group and a tightly bound, water molecule. The phenyl moiety of the hapten packs against two tyrosine, side chains at positions 50 and 106 in the heavy chain. Residue Arg-96 in, the light chain had been implicated as involved in hapten binding on the, basis of previous experiments, and indeed, this residue appears to play a, crucial role in this model. Experiments employing site-directed, mutagenesis directly support this conclusion. The heavy-chain, complementarity-determining regions have novel conformations not, previously observed in immunoglobulins except for the recently solved, anti-p-azophenylarsonate Fab R 19.9 (Lascombe et al., 1989).
About this StructureAbout this Structure
8FAB is a Protein complex structure of sequences from Homo sapiens. Full crystallographic information is available from OCA.
ReferenceReference
Three-dimensional structure of murine anti-p-azophenylarsonate Fab 36-71. 1. X-ray crystallography, site-directed mutagenesis, and modeling of the complex with hapten., Strong RK, Campbell R, Rose DR, Petsko GA, Sharon J, Margolies MN, Biochemistry. 1991 Apr 16;30(15):3739-48. PMID:2015229
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