1aqw
From Proteopedia
(New page: 200px<br /> <applet load="1aqw" size="450" color="white" frame="true" align="right" spinBox="true" caption="1aqw, resolution 1.8Å" /> '''GLUTATHIONE S-TRANSF...) |
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| - | [[Image:1aqw.gif|left|200px]]<br /> | + | [[Image:1aqw.gif|left|200px]]<br /><applet load="1aqw" size="350" color="white" frame="true" align="right" spinBox="true" |
| - | <applet load="1aqw" size=" | + | |
caption="1aqw, resolution 1.8Å" /> | caption="1aqw, resolution 1.8Å" /> | ||
'''GLUTATHIONE S-TRANSFERASE IN COMPLEX WITH GLUTATHIONE'''<br /> | '''GLUTATHIONE S-TRANSFERASE IN COMPLEX WITH GLUTATHIONE'''<br /> | ||
==Overview== | ==Overview== | ||
| - | BACKGROUND: Glutathione S-transferases (GSTs) are detoxification enzymes, found in all aerobic organisms, which catalyse the conjugation of | + | BACKGROUND: Glutathione S-transferases (GSTs) are detoxification enzymes, found in all aerobic organisms, which catalyse the conjugation of glutathione with a wide range of hydrophobic electrophilic substrates, thereby protecting the cell from serious damage caused by electrophilic compounds. GSTs are classified into five distinct classes (alpha, mu, pi, sigma and theta) by their substrate specificity and primary structure. Human GSTs are of interest because tumour cells show increased levels of expression of single classes of GSTs, which leads to drug resistance. Structural differences between classes of GST can therefore be utilised to develop new anti-cancer drugs. Many mutational and structural studies have been carried out on the mu and alpha classes of GST to elucidate the reaction mechanism, whereas knowledge about the pi class is still limited. RESULTS: We have solved the structures of the pi class GST hP1-1 in complex with its substrate, glutathione, a transition-state complex, the Meisenheimer complex, and an inhibitor, S-(rho-bromobenzyl)-glutathione, and refined them to resolutions of 1.8 A, 2.0 A and 1.9 A, respectively. All ligand molecules are well-defined in the electron density. In all three structures, an additionally bound N-morpholino-ethansulfonic acid molecule from the buffer solution was found. CONCLUSIONS: In the structure of the GST-glutathione complex, two conserved water molecules are observed, one of which hydrogen bonds directly to the sulphur atom of glutathione and the other forms hydrogen bonds with residues around the glutathione-binding site. These water molecules are absent from the structure of the Meisenheimer complex bound to GST, implicating that deprotonation of the cysteine occurs during formation of the ternary complex which involves expulsion of the inner bound water molecule. The comparison of our structures with known mu class GST structures show differences in the location of the electrophile-binding site (H-site), explaining the different substrate specificities of the two classes. Fluorescence measurements are in agreement with the position of the N-morpholino-ethansulfonic acid, close to Trp28, identifying a possible ligandin-substrate binding site. |
==About this Structure== | ==About this Structure== | ||
| - | 1AQW is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] with MES as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Glutathione_transferase Glutathione transferase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.5.1.18 2.5.1.18] Full crystallographic information is available from [http:// | + | 1AQW is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] with <scene name='pdbligand=MES:'>MES</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Glutathione_transferase Glutathione transferase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.5.1.18 2.5.1.18] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1AQW OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Homo sapiens]] | [[Category: Homo sapiens]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Fahl, W | + | [[Category: Fahl, W E.]] |
[[Category: Huber, R.]] | [[Category: Huber, R.]] | ||
| - | [[Category: Manoharan, T | + | [[Category: Manoharan, T H.]] |
[[Category: Prade, L.]] | [[Category: Prade, L.]] | ||
[[Category: Reuter, W.]] | [[Category: Reuter, W.]] | ||
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[[Category: transferase]] | [[Category: transferase]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 11:47:21 2008'' |
Revision as of 09:47, 21 February 2008
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GLUTATHIONE S-TRANSFERASE IN COMPLEX WITH GLUTATHIONE
Overview
BACKGROUND: Glutathione S-transferases (GSTs) are detoxification enzymes, found in all aerobic organisms, which catalyse the conjugation of glutathione with a wide range of hydrophobic electrophilic substrates, thereby protecting the cell from serious damage caused by electrophilic compounds. GSTs are classified into five distinct classes (alpha, mu, pi, sigma and theta) by their substrate specificity and primary structure. Human GSTs are of interest because tumour cells show increased levels of expression of single classes of GSTs, which leads to drug resistance. Structural differences between classes of GST can therefore be utilised to develop new anti-cancer drugs. Many mutational and structural studies have been carried out on the mu and alpha classes of GST to elucidate the reaction mechanism, whereas knowledge about the pi class is still limited. RESULTS: We have solved the structures of the pi class GST hP1-1 in complex with its substrate, glutathione, a transition-state complex, the Meisenheimer complex, and an inhibitor, S-(rho-bromobenzyl)-glutathione, and refined them to resolutions of 1.8 A, 2.0 A and 1.9 A, respectively. All ligand molecules are well-defined in the electron density. In all three structures, an additionally bound N-morpholino-ethansulfonic acid molecule from the buffer solution was found. CONCLUSIONS: In the structure of the GST-glutathione complex, two conserved water molecules are observed, one of which hydrogen bonds directly to the sulphur atom of glutathione and the other forms hydrogen bonds with residues around the glutathione-binding site. These water molecules are absent from the structure of the Meisenheimer complex bound to GST, implicating that deprotonation of the cysteine occurs during formation of the ternary complex which involves expulsion of the inner bound water molecule. The comparison of our structures with known mu class GST structures show differences in the location of the electrophile-binding site (H-site), explaining the different substrate specificities of the two classes. Fluorescence measurements are in agreement with the position of the N-morpholino-ethansulfonic acid, close to Trp28, identifying a possible ligandin-substrate binding site.
About this Structure
1AQW is a Single protein structure of sequence from Homo sapiens with as ligand. Active as Glutathione transferase, with EC number 2.5.1.18 Full crystallographic information is available from OCA.
Reference
Structures of class pi glutathione S-transferase from human placenta in complex with substrate, transition-state analogue and inhibitor., Prade L, Huber R, Manoharan TH, Fahl WE, Reuter W, Structure. 1997 Oct 15;5(10):1287-95. PMID:9351803
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