1bay
From Proteopedia
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| , resolution 2.0Å | |||||||
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| Activity: | Glutathione transferase, with EC number 2.5.1.18 | ||||||
| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
GLUTATHIONE S-TRANSFERASE YFYF CYS 47-CARBOXYMETHYLATED CLASS PI, FREE ENZYME
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
1BAY is a Single protein structure of sequence from Mus musculus. 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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