1uc5

Structure of diol dehydratase complexed with (R)-1,2-propanediol

spinqualitylabelsall models 1uc5, resolution 2.30Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1uc5 is a 6 chain structure with sequence from Klebsiella oxytoca. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.3Å Ligands: CNC, K, NH4, PGR Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function Q59470_KLEOX 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 Adenosylcobalamin-dependent diol dehydratase of Klebsiella oxytoca is apparently not stereospecific and catalyzes the conversion of both (R)- and (S)-1,2-propanediol to propionaldehyde. To explain this unusual property of the enzyme, we analyzed the crystal structures of diol dehydratase in complexes with cyanocobalamin and (R)- or (S)-1,2-propanediol. (R)- and (S)-isomers are bound in a symmetrical manner, although the hydrogen-bonding interactions between the substrate and the active-site residues are the same. From the position of the adenosyl radical in the modeled "distal" conformation, it is reasonable for the radical to abstract the pro-R and pro-S hydrogens from (R)- and (S)-isomers, respectively. The hydroxyl groups in the substrate radicals would migrates from C(2) to C(1) by a suprafacial shift, resulting in the stereochemical inversion at C(1). This causes 60 degrees clockwise and 70 degrees counterclockwise rotations of the C(1)-C(2) bond of the (R)- and (S)-isomers, respectively, if viewed from K+. A modeling study of 1,1-gem-diol intermediates indicated that new radical center C(2) becomes close to the methyl group of 5'-deoxyadenosine. Thus, the hydrogen back-abstraction (recombination) from 5'-deoxyadenosine by the product radical is structurally feasible. It was also predictable that the substitution of the migrating hydroxyl group by a hydrogen atom from 5'-deoxyadenosine takes place with the inversion of the configuration at C(2) of the substrate. Stereospecific dehydration of the 1,1-gem-diol intermediates can also be rationalized by assuming that Asp-alpha335 and Glu-alpha170 function as base catalysts in the dehydration of the (R)- and (S)-isomers, respectively. The structure-based mechanism and stereochemical courses of the reaction are proposed. Structural rationalization for the lack of stereospecificity in coenzyme B12-dependent diol dehydratase.,Shibata N, Nakanishi Y, Fukuoka M, Yamanishi M, Yasuoka N, Toraya T J Biol Chem. 2003 Jun 20;278(25):22717-25. Epub 2003 Apr 8. PMID:12684496 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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