1yve
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(New page: 200px<br /><applet load="1yve" size="450" color="white" frame="true" align="right" spinBox="true" caption="1yve, resolution 1.65Å" /> '''ACETOHYDROXY ACID IS...)
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Revision as of 04:57, 21 November 2007
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ACETOHYDROXY ACID ISOMEROREDUCTASE COMPLEXED WITH NADPH, MAGNESIUM AND INHIBITOR IPOHA (N-HYDROXY-N-ISOPROPYLOXAMATE)
Overview
Acetohydroxy acid isomeroreductase catalyzes the conversion of, acetohydroxy acids into dihydroxy valerates. This reaction is the second, in the synthetic pathway of the essential branched side chain amino acids, valine and isoleucine. Because this pathway is absent from animals, the, enzymes involved in it are good targets for a systematic search for, herbicides. The crystal structure of acetohydroxy acid isomeroreductase, complexed with cofactor NADPH, Mg2+ ions and a competitive inhibitor with, herbicidal activity, N-hydroxy-N-isopropyloxamate, was solved to 1.65 A, resolution and refined to an R factor of 18.7% and an R free of 22.9%. The, asymmetric unit shows two functional dimers related by, non-crystallographic symmetry. The active site, nested at the interface, between the NADPH-binding domain and the all-helical C-terminus domain, shows a situation analogous to the transition state. It contains two Mg2+, ions interacting with the inhibitor molecule and bridged by the, carboxylate moiety of an aspartate residue. The inhibitor-binding site is, well adjusted to it, with a hydrophobic pocket and a polar region. Only 24, amino acids are conserved among known acetohydroxy acid isomeroreductase, sequences and all of these are located around the active site. Finally, a, 140 amino acid region, present in plants but absent from other species, was found to make up most of the dimerization domain.
About this Structure
1YVE is a Single protein structure of sequence from Spinacia oleracea with MG, CL, NDP and HIO as ligands. Active as Ketol-acid reductoisomerase, with EC number 1.1.1.86 Full crystallographic information is available from OCA.
Reference
The crystal structure of plant acetohydroxy acid isomeroreductase complexed with NADPH, two magnesium ions and a herbicidal transition state analog determined at 1.65 A resolution., Biou V, Dumas R, Cohen-Addad C, Douce R, Job D, Pebay-Peyroula E, EMBO J. 1997 Jun 16;16(12):3405-15. PMID:9218783
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