1gti
From Proteopedia
(New page: 200px<br /><applet load="1gti" size="450" color="white" frame="true" align="right" spinBox="true" caption="1gti, resolution 3.0Å" /> '''MODIFIED GLUTATHIONE ...) |
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| - | [[Image:1gti.gif|left|200px]]<br /><applet load="1gti" size=" | + | [[Image:1gti.gif|left|200px]]<br /><applet load="1gti" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1gti, resolution 3.0Å" /> | caption="1gti, resolution 3.0Å" /> | ||
'''MODIFIED GLUTATHIONE S-TRANSFERASE (PI) COMPLEXED WITH S (P-NITROBENZYL)GLUTATHIONE'''<br /> | '''MODIFIED GLUTATHIONE S-TRANSFERASE (PI) COMPLEXED WITH S (P-NITROBENZYL)GLUTATHIONE'''<br /> | ||
==Overview== | ==Overview== | ||
| - | The three-dimensional structure of mouse liver glutathione S-transferase | + | The three-dimensional structure of mouse liver glutathione S-transferase P1-1 carboxymethylated at Cys-47 and its complex with S-(p-nitrobenzyl)glutathione have been determined by x-ray diffraction analysis. The structure of the modified enzyme described here is the first structural report for a Pi class glutathione S-transferase with no glutathione, glutathione S-conjugate, or inhibitor bound. It shows that part of the active site area, which includes helix alphaB and helix 310B, is disordered. However, the environment of Tyr-7, an essential residue for the catalytic reaction, remains unchanged. The position of the sulfur atom of glutathione is occupied in the ligand-free enzyme by a water molecule that is at H-bond distance from Tyr-7. We do not find any structural evidence for a tyrosinate form, and therefore our results suggest that Tyr-7 is not acting as a general base abstracting the proton from the thiol group of glutathione. The binding of the inhibitor S-(p-nitrobenzyl)-glutathione to the carboxymethylated enzyme results in a partial restructuring of the disordered area. The modification of Cys-47 sterically hinders structural organization of this region, and although it does not prevent glutathione binding, it significantly reduces the affinity. A detailed kinetic study of the modified enzyme indicates that the carboxymethylation increases the Km for glutathione by 3 orders of magnitude, although the enzyme can function efficiently under saturating conditions. |
==About this Structure== | ==About this Structure== | ||
| - | 1GTI is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Mus_musculus Mus musculus] with GTB 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:// | + | 1GTI is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Mus_musculus Mus musculus] with <scene name='pdbligand=GTB:'>GTB</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=1GTI OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Coll, M.]] | [[Category: Coll, M.]] | ||
| - | [[Category: Vega, M | + | [[Category: Vega, M C.]] |
[[Category: GTB]] | [[Category: GTB]] | ||
[[Category: glutathione]] | [[Category: glutathione]] | ||
[[Category: transferase]] | [[Category: transferase]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:53:45 2008'' |
Revision as of 10:53, 21 February 2008
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MODIFIED GLUTATHIONE S-TRANSFERASE (PI) COMPLEXED WITH S (P-NITROBENZYL)GLUTATHIONE
Overview
The three-dimensional structure of mouse liver glutathione S-transferase P1-1 carboxymethylated at Cys-47 and its complex with S-(p-nitrobenzyl)glutathione have been determined by x-ray diffraction analysis. The structure of the modified enzyme described here is the first structural report for a Pi class glutathione S-transferase with no glutathione, glutathione S-conjugate, or inhibitor bound. It shows that part of the active site area, which includes helix alphaB and helix 310B, is disordered. However, the environment of Tyr-7, an essential residue for the catalytic reaction, remains unchanged. The position of the sulfur atom of glutathione is occupied in the ligand-free enzyme by a water molecule that is at H-bond distance from Tyr-7. We do not find any structural evidence for a tyrosinate form, and therefore our results suggest that Tyr-7 is not acting as a general base abstracting the proton from the thiol group of glutathione. The binding of the inhibitor S-(p-nitrobenzyl)-glutathione to the carboxymethylated enzyme results in a partial restructuring of the disordered area. The modification of Cys-47 sterically hinders structural organization of this region, and although it does not prevent glutathione binding, it significantly reduces the affinity. A detailed kinetic study of the modified enzyme indicates that the carboxymethylation increases the Km for glutathione by 3 orders of magnitude, although the enzyme can function efficiently under saturating conditions.
About this Structure
1GTI is a Single protein structure of sequence from Mus musculus with as ligand. Active as Glutathione transferase, with EC number 2.5.1.18 Full crystallographic information is available from OCA.
Reference
The three-dimensional structure of Cys-47-modified mouse liver glutathione S-transferase P1-1. Carboxymethylation dramatically decreases the affinity for glutathione and is associated with a loss of electron density in the alphaB-310B region., Vega MC, Walsh SB, Mantle TJ, Coll M, J Biol Chem. 1998 Jan 30;273(5):2844-50. PMID:9446594
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