1yfy
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(New page: 200px<br /><applet load="1yfy" size="450" color="white" frame="true" align="right" spinBox="true" caption="1yfy, resolution 3.20Å" /> '''Crystal structure of...)
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Revision as of 04:37, 21 November 2007
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Crystal structure of 3-hydroxyanthranilate-3,4-dioxygenase from Ralstonia metallidurans complexed with 3-hydroxyanthranilic acid
Overview
3-Hydroxyanthranilate-3,4-dioxygenase (HAD) catalyzes the oxidative ring, opening of 3-hydroxyanthranilate in the final enzymatic step of the, biosynthetic pathway from tryptophan to quinolinate, the universal de novo, precursor to the pyridine ring of nicotinamide adenine dinucleotide. The, enzyme requires Fe2+ as a cofactor and is inactivated by, 4-chloro-3-hydroxyanthranilate. HAD from Ralstonia metallidurans was, crystallized, and the structure was determined at 1.9 A resolution. The, structures of HAD complexed with the inhibitor, 4-chloro-3-hydroxyanthranilic acid and either molecular oxygen or nitric, oxide were determined at 2.0 A resolution, and the structure of HAD, complexed with 3-hydroxyanthranilate was determined at 3.2 A resolution., HAD is a homodimer with a subunit topology that is characteristic of the, cupin barrel fold. Each monomer contains two iron binding sites. The, catalytic iron is buried deep inside the beta-barrel with His51, Glu57, and His95 serving as ligands. The other iron site forms an FeS4 center, close to the solvent surface in which the sulfur atoms are provided by, Cys125, Cys128, Cys162, and Cys165. The two iron sites are separated by 24, A. On the basis of the crystal structures of HAD, mutagenesis studies were, carried out in order to elucidate the enzyme mechanism. In addition, a new, mechanism for the enzyme inactivation by 4-chloro-3-hydroxyanthranilate is, proposed.
About this Structure
1YFY is a Single protein structure of sequence from Cupriavidus metallidurans with FE, TRS and 3HA as ligands. Active as 3-hydroxyanthranilate 3,4-dioxygenase, with EC number 1.13.11.6 Full crystallographic information is available from OCA.
Reference
Structural studies on 3-hydroxyanthranilate-3,4-dioxygenase: the catalytic mechanism of a complex oxidation involved in NAD biosynthesis., Zhang Y, Colabroy KL, Begley TP, Ealick SE, Biochemistry. 2005 May 31;44(21):7632-43. PMID:15909978
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