Modulation of Class Pi glutathione transferase activity by sulfhydryl group modification

Shen, Hongxie; Tamai, Katsuto; Satoh, Keisuke; Hatayama, Ichiro; Tsuchida, Shigeki; Sato, Kei

doi:10.1016/0003-9861(91)90025-e

Cited by 66 publications

(34 citation statements)

References 14 publications

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“…with the previous reports (1)(2)(3)(4)(5). The underlying reasons of reduced lens GPx, GR and GST activities in advanced disease are highly complex, as can be the result of downregulated or insufficiently expressed genes (14), as well as oxidative modifications of enzymatic molecules, potentiated by extensive loss of the cellular GSH pool (25,26). As shown in our study, the concentration of lenticular GSH was independently associated with cataract maturity [OR 17.93 (CI 4.04-79.63); p=0.0001], thereby confirming its pi votal antioxidant role in this organ, as emphasized by others (3).…”

Section: Discussionsupporting

confidence: 55%

The Impact of Senile Cataract Maturity on Blood Oxidative Stress Markers and Glutathione-Dependent Antioxidants: Relations with Lens Variables

Mirić¹,

Kisic²,

Zoric³

et al. 2012

Journal of Medical Biochemistry

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The Impact of Senile Cataract Maturity on Blood Oxidative Stress Markers and Glutathione-Dependent Antioxidants: Relations with Lens VariablesOxidative stress is implicated in senile cataract (SC) genesis, although the impact of SC maturity on blood oxidative stress markers is unclear. Total hydroperoxides, malondialdehyde (MDA), glutathione (GSH), glutathione peroxidase (GPx), glutathione reductase (GR) and glutathione S-transferase (GST) were measured in the blood and lens samples of patients having either immature (n=31) or mature SC (n=50), and in 22 blood samples from noncataract controls. Compared to controls, SC patients had higher plasma MDA and serum GST, and decreased plasma GR and GSH levels. Plasma GPx as well as hydroperoxides differed from control values only in patients with mature SC. The multivariate logistic regression analysis showed that the fall of plasma GR activity (OR 5.14; CI 1.82-14.51;p=0.0020), as well as serum GST activity (OR 3.84; CI 1.36-10.83;p=0.0108) were independently associated with the maturity of SC. Lens hydroperoxides, MDA and GST, showed no correlation with correspondent blood values, in contrast to GPx (r=0.715; p<0.001) and GR (r=0.703; p<0.001). This study showed that the severity of SC is associated with increased systemic oxidative stress, which could be due to the fall of GSH-dependent antioxidant enzymes activities.

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Section: Discussionsupporting

confidence: 55%

The Impact of Senile Cataract Maturity on Blood Oxidative Stress Markers and Glutathione-Dependent Antioxidants: Relations with Lens Variables

Mirić¹,

Kisic²,

Zoric³

et al. 2012

Journal of Medical Biochemistry

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“…A number of amino acid residues, Trp 39 , Lys 45 , Gln 52 , and the NH group of Leu 53 , that have H-bond interaction with GSH, contribute to the G-site (37). Chemical modification of the reactive Cys 48 (38 -40), intramonomer disulfide bond formation between Cys 48 and Cys 102 (41,42) and proteolytic cleavage of the peptide bond between Lys 45 and Ala 46 by trypsin (43), as well as structural evidence, based on x-ray crystallographic and NMR studies (44,45) demonstrate that this region is highly flexible in the absence of GSH and is stabilized by GSH binding to the active site. Thus any mutation, e.g.…”

Section: Effect Of Key Residue On Dimer Formation and Thermalmentioning

confidence: 99%

“…On the other hand, mutants Y50F (24) and Y50A (the present study) display negative cooperativity of GSH binding. Caccuri et al (24) suggested that Gly 42 , Cys 48 , and Lys 55 point mutations induce cooperativity by distorting the conformation of helix ␣2. The structural effect in one G-site was assumed to be transmitted to the second one through Tyr 50 and helix ␣4, which are located at the dimer interface.…”

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confidence: 99%

Functional Role of the Lock and Key Motif at the Subunit Interface of Glutathione Transferase P1-1

Hegazy¹,

Mannervik

Stenberg

2004

Journal of Biological Chemistry

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The glutathione transferases (GSTs) represent a superfamily of dimeric proteins. Each subunit has an active site, but there is no evidence for the existence of catalytically active monomers. The lock and key motif is responsible for a highly conserved hydrophobic interaction in the subunit interface of pi, mu, and alpha class glutathione transferases. The key residue, which is either Phe or Tyr (Tyr 50 in human GSTP1-1) in one subunit, is wedged into a hydrophobic pocket of the other subunit. To study how an essentially inactive subunit influences the activity of the neighboring subunit, we have generated the heterodimer composed of subunits from the fully active human wild-type GSTP1-1 and the nearly inactive mutant Y50A obtained by mutation of the key residue Tyr 50 to Ala. Although the key residue is located far from the catalytic center, the k cat value of mutant Y50A decreased about 1300-fold in comparison with the wild-type enzyme. The decrease of the k cat value of the heterodimer by about 27-fold rather than the expected 2-fold in comparison with the wild-type enzyme indicates that the two active sites of the dimeric enzyme work synergistically. Further evidence for cooperativity was found in the nonhyperbolic GSH saturation curves. A network of hydrogen-bonded water molecules, found in crystal structures of GSTP1-1, connects the two active sites and the main chain carbonyl group of Tyr 50 , thereby offering a mechanism for communication between the two active sites. It is concluded that a subunit becomes catalytically competent by positioning the key residue of one subunit into the lock pocket of the other subunit, thereby stabilizing the loop following the helix ␣2, which interacts directly with GSH.

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“…Indeed this appears to be a feature of all class Pi structures solved to date (8,9,13). This is important because some authors (23)(24)(25) have presented a considerable body of evidence that implicates the availability of cysteine 47 for mixed disulfide formation as a redox sensor. Cystine forms a mixed disulfide with GST P1-1 in agreement with this hypothesis (24).…”

mentioning

confidence: 99%

The Three-dimensional Structure of Cys-47-modified Mouse Liver Glutathione S-Transferase P1-1

Vega¹,

Walsh²,

Mantle³

et al. 1998

Journal of Biological Chemistry

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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 P i 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 ␣B and helix 3 10 B, 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 K m for glutathione by 3 orders of magnitude, although the enzyme can function efficiently under saturating conditions.

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Modulation of Class Pi glutathione transferase activity by sulfhydryl group modification

Cited by 66 publications

References 14 publications

The Impact of Senile Cataract Maturity on Blood Oxidative Stress Markers and Glutathione-Dependent Antioxidants: Relations with Lens Variables

The Impact of Senile Cataract Maturity on Blood Oxidative Stress Markers and Glutathione-Dependent Antioxidants: Relations with Lens Variables

Functional Role of the Lock and Key Motif at the Subunit Interface of Glutathione Transferase P1-1

The Three-dimensional Structure of Cys-47-modified Mouse Liver Glutathione S-Transferase P1-1

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