1t66

The structure of FAB with intermediate affinity for fluorescein.

spinqualitylabelsall models 1t66, resolution 2.30Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1t66 is a 4 chain structure with sequence from Mus musculus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: FLU Related: 1flr Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed Multi-disciplinary studies of fluorescein-protein conjugates have led to the generation of a family of antibodies with common idiotypes and affinities for fluorescein ranging over five orders of magnitude. The high affinity 4-4-20 prototype traps the ligand in a highly complementary binding slot, which is lined by multiple aromatic side-chains. An antibody (9-40) of intermediate affinity belongs to the same idiotypic family as 4-4-20 and shares substantial amino acid identities within the VL and VH domains. To establish the structural basis for the affinity differences, we solved the crystal structure of the 9-40 Fab-fluorescein complex at a resolution of 2.3A. Similar to 4-4-20, 9-40 binds fluorescein in a tight aromatic slot with its xanthenonyl ring system accommodated by end-on insertion. However, the combined effects of the amino acid substitutions have resulted in reorganization of the binding site, with the HCDR3 loops showing the greatest differences in conformations. Access to the binding site of 9-40 is substantially more open, leaving the fluorescein's phenylcarboxylate moiety partially exposed to solvent. In addition to the usage of a different D (diversity) mini-gene encoding the HCDR3 loop, the decrease in fluorescein affinity in the 9-40 antibody family appears to be correlated with the substitution of histidine (9-40) for arginine (4-4-20) in position 34 of the antibody light chains. Three-dimensional structures of idiotypically related Fabs with intermediate and high affinity for fluorescein.,Terzyan S, Ramsland PA, Voss EW Jr, Herron JN, Edmundson AB J Mol Biol. 2004 Jun 18;339(5):1141-51. PMID:15178254 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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