Glutathione oxidised reductase

Figure 5.3. The glutathione cycle. Abbreviations HMP, hexose monophosphate shunt GSH, reduced glutathione GSSH, oxidised glutathione GR, glutathione reductase GPO, glutathione peroxidase. In the system shown, H2O2 is converted into H20, but the system is also effective in breaking down organic peroxides.

Fig. 11. Sketch of one active site of the dimeric enzyme glutathione reductase, from the work of Schulz and colleagues [53]. Oxidised glutathione binds between subunits. Hydrogen is transferred via the FAD.

Subchronic exposure to MnCb for 7 days (total dose 1750 pmol/kg) by means of mini-osmotic pumps inplanted s.c. produced significant reduction in GSH-peroxidase (EC 1.11.1.9) activity in the cytosol and mitochondrial fractions of the whole rat brain and the striatum (Liccione and Maines 1988). The decrease in GSH-peroxidase was most pronounced in the mitochondrial fraction of the striatum where the activity was reduced to 35 % of the control. Catalase (EC 1.11.1.6) activity was also decreased in the striatum of rats treated with Mn but not in the whole brain. GSH content was markedly depleted (20 % of the control) in the striatum, although only modestly decreased in the whole brain (80% of the control). The treatment of rats with Mn also decreased the activity of oxidised glutathione reductase (EC 1.6.4.2) the same treatment increased the activity of y-glutamyltranspeptidase (EC 2.3.2.2). The activity of y-glutamylcysteine synthetase was not altered by Mn. 

---