Effect of glutathione, glutathione sulphonate and S‐hexylglutathione on the conformational stability of class pi glutathione S‐transferase

FEBS Letters

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