1axe

CRYSTAL STRUCTURE OF THE ACTIVE-SITE MUTANT PHE93->TRP OF HORSE LIVER ALCOHOL DEHYDROGENASE IN COMPLEX WITH NAD AND INHIBITOR TRIFLUOROETHANOL

spinqualitylabelsall models 1axe, resolution 2.00Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1axe is a 2 chain structure with sequence from Equus caballus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2Å Ligands: ETF, NAD, ZN Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function ADH1E_HORSE 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 We present evidence that the size of an active site side chain may modulate the degree of hydrogen tunneling in an enzyme-catalyzed reaction. Primary and secondary kH/kT and kD/kT kinetic isotope effects have been measured for the oxidation of benzyl alcohol catalyzed by horse liver alcohol dehydrogenase at 25 degrees C. As reported in earlier studies, the relationship between secondary kH/kT and kD/kT isotope effects provides a sensitive probe for deviations from classical behavior. In the present work, catalytic efficiency and the extent of hydrogen tunneling have been correlated for the alcohol dehydrogenase-catalyzed hydride transfer among a group of site-directed mutants at position 203. Val-203 interacts with the opposite face of the cofactor NAD+ from the alcohol substrate. The reduction in size of this residue is correlated with diminished tunneling and a two orders of magnitude decrease in catalytic efficiency. Comparison of the x-ray crystal structures of a ternary complex of a high-tunneling (Phe-93 --> Trp) and a low-tunneling (Val-203 --> Ala) mutant provides a structural basis for the observed effects, demonstrating an increase in the hydrogen transfer distance for the low-tunneling mutant. The Val-203 --> Ala ternary complex crystal structure also shows a hyperclosed interdomain geometry relative to the wild-type and the Phe-93 --> Trp mutant ternary complex structures. This demonstrates a flexibility in interdomain movement that could potentially narrow the distance between the donor and acceptor carbons in the native enzyme and may enhance the role of tunneling in the hydride transfer reaction. A link between protein structure and enzyme catalyzed hydrogen tunneling.,Bahnson BJ, Colby TD, Chin JK, Goldstein BM, Klinman JP Proc Natl Acad Sci U S A. 1997 Nov 25;94(24):12797-802. PMID:9371755 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Alcohol dehydrogenase 3D structures

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