1ib6

CRYSTAL STRUCTURE OF R153C E. COLI MALATE DEHYDROGENASE

spinqualitylabelsall models 1ib6, resolution 2.10Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1ib6 is a 4 chain structure with sequence from "bacillus_coli"_migula_1895 "bacillus coli" migula 1895. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: NAD, SO4 Gene: MDH ("Bacillus coli" Migula 1895) Activity: Malate dehydrogenase, with EC number 1.1.1.37 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [MDH_ECOLI] Catalyzes the reversible oxidation of malate to oxaloacetate.[HAMAP-Rule:MF_01516] 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 Malate dehydrogenase specifically oxidizes malate to oxaloacetate. The specificity arises from three arginines in the active site pocket that coordinate the carboxyl groups of the substrate and stabilize the newly forming hydroxyl/keto group during catalysis. Here, the role of Arg-153 in distinguishing substrate specificity is examined by the mutant R153C. The x-ray structure of the NAD binary complex at 2.1 A reveals two sulfate ions bound in the closed form of the active site. The sulfate that occupies the substrate binding site has been translated approximately 2 A toward the opening of the active site cavity. Its new location suggests that the low catalytic turnover observed in the R153C mutant may be due to misalignment of the hydroxyl or ketone group of the substrate with the appropriate catalytic residues. In the NAD.pyruvate ternary complex, the monocarboxylic inhibitor is bound in the open conformation of the active site. The pyruvate is coordinated not by the active site arginines, but through weak hydrogen bonds to the amide backbone. Energy minimized molecular models of unnatural analogues of R153C (Wright, S. K., and Viola, R. E. (2001) J. Biol. Chem. 276, 31151-31155) reveal that the regenerated amino and amido side chains can form favorable hydrogen-bonding interactions with the substrate, although a return to native enzymatic activity is not observed. The low activity of the modified R153C enzymes suggests that precise positioning of the guanidino side chain is essential for optimal orientation of the substrate. Structural analyses of a malate dehydrogenase with a variable active site.,Bell JK, Yennawar HP, Wright SK, Thompson JR, Viola RE, Banaszak LJ J Biol Chem. 2001 Aug 17;276(33):31156-62. Epub 2001 Jun 1. PMID:11389141 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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