1GTI

MODIFIED GLUTATHIONE S-TRANSFERASE (PI) COMPLEXED WITH S (P-NITROBENZYL)GLUTATHIONE

Summary for 1GTI

• Entry DOI: 10.2210/pdb1gti/pdb
• Descriptor: GLUTATHIONE S-TRANSFERASE, S-(P-NITROBENZYL)GLUTATHIONE (2 entities in total)
• Functional Keywords: glutathione, transferase
• Biological source: Mus musculus (house mouse)
• Total number of polymer chains: 6
• Total formula weight: 144026.66

Authors

Vega, M.C.,Coll, M. (deposition date: 1998-01-09, release date: 1999-03-02, Last modification date: 2023-08-09)

Primary citation

Vega, M.C.,Walsh, S.B.,Mantle, T.J.,Coll, M.
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.
J.Biol.Chem., 273:2844-2850, 1998

PubMed Abstract: 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.

PubMed: 9446594
DOI: 10.1074/jbc.273.5.2844

Experimental method

X-RAY DIFFRACTION (3 Å)