1gnw
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(New page: 200px<br /><applet load="1gnw" size="450" color="white" frame="true" align="right" spinBox="true" caption="1gnw, resolution 2.2Å" /> '''STRUCTURE OF GLUTATHI...)
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Revision as of 14:04, 20 November 2007
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STRUCTURE OF GLUTATHIONE S-TRANSFERASE
Overview
Glutathione S-transferases (GST) are a family of multifunctional enzymes, involved in the metabolization of a broad variety of xenobiotics and, reactive endogenous compounds. The interest in plant glutathione, S-transferases may be attributed to their agronomic value, since it has, been demonstrated that glutathione conjugation for a variety of herbicides, is the major resistance and selectivity factor in plants. The, three-dimensional structure of glutathione S-transferase from the plant, Arabidopsis thaliana has been solved by multiple isomorphous replacement, and multiwavelength anomalous dispersion techniques at 3 A resolution and, refined to a final crystallographic R-factor of 17.5% using data from 8 to, 2.2 A resolution. The enzyme forms a dimer of two identical subunits each, consisting of 211 residues. Each subunit is characterized by the, GST-typical modular structure with two spatially distinct domains. Domain, I consists of a central four-stranded beta-sheet flanked on one side by, two alpha-helices and on the other side by an irregular segment containing, three short 3(10)-helices, while domain II is entirely helical. The, dimeric molecule is globular with a prominent large cavity formed between, the two subunits. The active site is located in a cleft situated between, domains I and II and each subunit binds two molecules of a competitive, inhibitor S-hexylglutathione. Both hexyl moieties are oriented parallel, and fill the H-subsite of the enzyme's active site. The glutathione, peptide of one inhibitor, termed productive binding, occupies the, G-subsite with multiple interactions similar to those observed for other, glutathione S-transferases, while the glutathione backbone of the second, inhibitor, termed unproductive binding, exhibits only weak interactions, mediated by two polar contacts. A most striking difference from the, mammalian glutathione S-transferases, which share a conserved catalytic, tyrosine residue, is the lack of this tyrosine in the active site of the, plant glutathione S-transferase.
About this Structure
1GNW is a Single protein structure of sequence from Arabidopsis thaliana with GTX as ligand. Active as Glutathione transferase, with EC number 2.5.1.18 Full crystallographic information is available from OCA.
Reference
Three-dimensional structure of glutathione S-transferase from Arabidopsis thaliana at 2.2 A resolution: structural characterization of herbicide-conjugating plant glutathione S-transferases and a novel active site architecture., Reinemer P, Prade L, Hof P, Neuefeind T, Huber R, Zettl R, Palme K, Schell J, Koelln I, Bartunik HD, Bieseler B, J Mol Biol. 1996 Jan 19;255(2):289-309. PMID:8551521
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