FEBS Letters | |
Effect of glutathione, glutathione sulphonate and S‐hexylglutathione on the conformational stability of class pi glutathione S‐transferase | |
Dirr, Heini1  Erhardt, Julija1  | |
[1] Protein Structure-Function Research Programme, Department of Biochemistry, University of the Witwatersrand, Johannesburg 2050, South Africa | |
关键词: Conformational stability; Unfolding; Denaturation; Glutathione S-transferase; Ligand binding; Glutathione; GST; glutathione S-transferase; pGST P1-1; porcine glutathione S-transferase class pi with two type-1 subunits; GSH; reduced glutathione; S-hexGSH; S-hexylglutathione; G-site; glutathione-binding site; H-site; hydrophobic binding site for electrophiles; | |
DOI : 10.1016/0014-5793(96)00768-5 | |
学科分类:生物化学/生物物理 | |
来源: John Wiley & Sons Ltd. | |
【 摘 要 】
The glutathione S-transferases (GST) are a supergene family of phase II detoxification enzymes which catalyse the S-conjugation between glutathione and an electrophilic substrate. The active site can be divided into two adjacent functional regions, a highly specific G-site for binding the physiological substrate glutathione and a nonspecific H-site for binding nonpolar electrophilic substrates. Equilibrium and kinetic unfolding experiments employing tryptophan fluorescence and enzyme activity measurements were performed to study the effect of ligand binding to the G-site on the unfolding and stability of the porcine class pi glutathione S-transferase against urea. The presence of glutathione caused a shift in the equilibrium-unfolding curves towards lower urea concentrations and enhanced the first-order rate constant for unfolding suggesting a destabilisation of the pGSTP1-1 structure against urea. The presence of either glutathione sulphonate or S-hexylglutathione, however, produced the opposite effect in that their binding to the G-site appeared to exert a stabilising effect against urea. The binding of these glutathione analogues also reduced significantly the degree of cooperativity of unfolding indicating a possible change in the protein's unfolding pathway.
【 授权许可】
Unknown
【 预 览 】
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