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1ydk
From Proteopedia
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'''Crystal structure of the I219A mutant of human glutathione transferase A1-1 with S-hexylglutathione''' | '''Crystal structure of the I219A mutant of human glutathione transferase A1-1 with S-hexylglutathione''' | ||
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[[Category: Sayed, Y.]] | [[Category: Sayed, Y.]] | ||
[[Category: Sewell, T.]] | [[Category: Sewell, T.]] | ||
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| - | [[Category: | + | [[Category: S-hexylglutathione]] |
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Revision as of 13:11, 3 May 2008
Crystal structure of the I219A mutant of human glutathione transferase A1-1 with S-hexylglutathione
Overview
The C-terminal region in class Alpha glutathione transferase A1-1 (GSTA1-1), which forms an amphipathic alpha-helix (helix 9), is known to contribute to the catalytic and non-substrate ligand-binding functions of the enzyme. The region in the apo protein is proposed to be disordered which, upon ligand binding at the active-site, becomes structured and localised. Because Ile219 plays a pivotal role in the stability and localisation of the region, the role of tertiary interactions mediated by Ile219 in determining the conformation and dynamics of the C-terminal region were studied. Ligand-binding microcalorimetric and X-ray structural data were obtained to characterise ligand binding at the active-site and the associated localisation of the C-terminal region. In the crystal structure of the I219A hGSTA1-1.S-hexylglutathione complex, the C-terminal region of one chain is mobile and not observed (unresolved electron density), whereas the corresponding region of the other chain is localised and structured as a result of crystal packing interactions. In solution, the mutant C-terminal region of both chains in the complex is mobile and delocalised resulting in a hydrated, less hydrophobic active-site and a reduction in the affinity of the protein for S-hexylglutathione. Complete dehydration of the active-site, important for maintaining the highly reactive thiolate form of glutathione, requires the binding of ligands and the subsequent localisation of the C-terminal region. Thermodynamic data demonstrate that the mobile C-terminal region in apo hGSTA1-1 is structured and does not undergo ligand-induced folding. Its close proximity to the surface of the wild-type protein is indicated by the concurrence between the observed heat capacity change of complex formation and the type and amount of surface area that becomes buried at the ligand-protein interface when the C-terminal region in the apo protein assumes the same localised structure as that observed in the wild-type complex.
About this Structure
1YDK is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.
Reference
Tertiary interactions stabilise the C-terminal region of human glutathione transferase A1-1: a crystallographic and calorimetric study., Kuhnert DC, Sayed Y, Mosebi S, Sayed M, Sewell T, Dirr HW, J Mol Biol. 2005 Jun 17;349(4):825-38. PMID:15893769 Page seeded by OCA on Sat May 3 16:11:29 2008
