1d5b

UNLIGANDED MATURE OXY-COPE CATALYTIC ANTIBODY

spinqualitylabelsall models 1d5b, resolution 2.80Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1d5b is a 4 chain structure. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: CD Related: 1axs, 1d5i, 1d6v 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 Antibody AZ-28 was generated against the chairlike transition-state analogue (TSA) 1 and catalyzes the oxy-Cope rearrangement of substrate 2 to product 3. The germline precursor to AZ-28 catalyzes the reaction with a 35-fold higher rate (k(cat)/k(uncat) = 163 000), despite a 40-fold lower binding affinity for TSA.1 (K(D) = 670 nM). To determine the structural basis for the differences in the binding and catalytic properties of the germline and affinity-matured antibodies, the X-ray crystal structures of the unliganded and TSA.1 complex of antibody AZ-28 have been determined at 2.8 and 2.6 A resolution, respectively; the structures of the unliganded and TSA.1 complex of the germline precursor to AZ-28 were both determined at 2. 0 A resolution. In the affinity-matured antibody.hapten complex the TSA is fixed in a catalytically unfavorable conformation by a combination of van der Waals and hydrogen-bonding interactions. The 2- and 5-phenyl substituents of TSA.1 are almost perpendicular to the cyclohexyl ring, leading to decreased orbital overlap and decreased stabilization of the putative transition state. The active site of the germline antibody appears to have an increased degree of flexibility-CDRH3 moves 4.9 A outward from the active site upon binding of TSA.1. We suggest that this conformational flexibility in the germline antibody, which results in a lower binding affinity for TSA.1, allows dynamic changes in the dihedral angle of the 2-phenyl substituent along the reaction coordinate. These conformational changes in turn lead to enhanced orbital overlap and increased catalytic rate. These studies suggest that protein and substrate dynamics play a key role in this antibody-catalyzed reaction. Conformational effects in biological catalysis: an antibody-catalyzed oxy-cope rearrangement.,Mundorff EC, Hanson MA, Varvak A, Ulrich H, Schultz PG, Stevens RC Biochemistry. 2000 Feb 1;39(4):627-32. PMID:10651626 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Monoclonal Antibodies 3D structures

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