9xia

X-RAY ANALYSIS OF D-XYLOSE ISOMERASE AT 1.9 ANGSTROMS: NATIVE ENZYME IN COMPLEX WITH SUBSTRATE AND WITH A MECHANISM-DESIGNED INACTIVATOR

spinqualitylabelsall models 9xia, resolution 1.90Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 9xia is a 1 chain structure with sequence from Streptomyces rubiginosus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: DFR, MN Activity: Xylose isomerase, with EC number 5.3.1.5 Resources: FirstGlance, OCA, RCSB, PDBsum 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 The structures of crystalline D-xylose isomerase (D-xylose ketol-isomerase; EC 5.3.1.5) from Streptomyces rubiginosus and of its complexes with substrate and with an active-site-directed inhibitor have been determined by x-ray diffraction techniques and refined to 1.9-A resolution. This study identifies the active site, as well as two metal-binding sites. The metal ions are important in maintaining the structure of the active-site region and one of them binds C3-O and C5-O of the substrate forming a six-membered ring. This study has revealed a very close contact between histidine and C1 of a substrate, suggesting that this is the active-site base that abstracts a proton from substrate. The mechanism-based inhibitor is a substrate analog and is turned over by the enzyme to give a product that alkylates this same histidine, reinforcing our interpretation. The changes in structure of the native enzyme, the enzyme with bound substrate, and the alkylated enzyme indicate that the mechanism involves an "open-chain" conformation of substrate and that the intermediate in the isomerization reaction is probably a cis-ene diol because the active-site histidine is correctly placed to abstract a proton from C1 or C2 of the substrate. A water molecule binds to C1O and C2O of the substrate and so may act as a proton donor or acceptor in the enolization of a ring-opened substrate. X-ray analysis of D-xylose isomerase at 1.9 A: native enzyme in complex with substrate and with a mechanism-designed inactivator.,Carrell HL, Glusker JP, Burger V, Manfre F, Tritsch D, Biellmann JF Proc Natl Acad Sci U S A. 1989 Jun;86(12):4440-4. PMID:2734296 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also D-xylose isomerase

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