1ogx

High Resolution Crystal Structure Of Ketosteroid Isomerase Mutant D40N(D38N, Ti Numbering) from Pseudomonas putida Complexed With Equilenin At 2.0 A Resolution.

spinqualitylabelsall models 1ogx, resolution 2.00Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1ogx is a 2 chain structure with sequence from Pseudomonas putida. This structure supersedes the now removed PDB entry 1e3n. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2Å Ligands: EQU Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function SDIS_PSEPU 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 Delta(5)-3-Ketosteroid isomerase catalyzes cleavage and formation of a C-H bond at a diffusion-controlled limit. By determining the crystal structures of the enzyme in complex with each of three different inhibitors and by nuclear magnetic resonance (NMR) spectroscopic investigation, we evidenced the ionization of a hydroxyl group (pK(a) approximately 16.5) of an inhibitor, which forms a low barrier hydrogen bond (LBHB) with a catalytic residue Tyr(14) (pK(a) approximately 11.5), and the protonation of the catalytic residue Asp(38) with pK(a) of approximately 4.5 at pH 6.7 in the interaction with a carboxylate group of an inhibitor. The perturbation of the pK(a) values in both cases arises from the formation of favorable interactions between inhibitors and catalytic residues. The results indicate that the pK(a) difference between catalytic residue and substrate can be significantly reduced in the active site environment as a result of the formation of energetically favorable interactions during the course of enzyme reactions. The reduction in the pK(a) difference should facilitate the abstraction of a proton and thereby eliminate a large fraction of activation energy in general acid/base enzyme reactions. The pK(a) perturbation provides a mechanistic ground for the fast reactivity of many enzymes and for the understanding of how some enzymes are able to extract a proton from a C-H group with a pK(a) value as high as approximately 30. Detection of large pKa perturbations of an inhibitor and a catalytic group at an enzyme active site, a mechanistic basis for catalytic power of many enzymes.,Ha NC, Kim MS, Lee W, Choi KY, Oh BH J Biol Chem. 2000 Dec 29;275(52):41100-6. PMID:11007792 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Ketosteroid Isomerase

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