Glutathione redox potential

V. Irihimovitch and M. Shapira. 2000. Glutathione redox potential modulated by reactive oxygen species regulates translation of rubisco large subunit in the chloroplast J. Biol. Chem. 275 16289-16295. (PubMed)... 

Gutscher M, Pauleau AL, Marty L et al (2008) Real-time imaging of the intracellular glutathione redox potential. Nat Methods 5(6) 553-559... 

Finally, the redox potential of the heterodisulfide CoB-S-S-CoM (22), which was synthesized according to known procedures [49], was measured under the same conditions in phosphate buffer at pH 7. An value of -143 10 mV vs SHE for 22 exhibits a more positive redox potential than typical disulfides such as glutathione and cysteine (E° =-204 6 mV vs SHE and E° =-202 3 mV vs. SHE, resp.). That these deviations are probably due to the presence of sulfonate... 

Fig. 8.2. Apparent standard redox potentials of oxidant and antioxidant species (GSH glutathione, AH- ascorbate, aT-OH a-tocopherol).

The couple with the higher E o value is capable of subtracting the e" of any couple with a lower value. As an example oxidized glutathione (GSSG) can be regenerated to 2 GSH (reduced glutathion) with a redox potential of E — 0.23 by... 

The redox potential within the cells is substantially lower than in the plasma (May and Williams, 1980), and may vary depending upon particular cellular biochemical activities and a myriad of potential redox couples such as reduced and oxidized glutathione species. In general, greater levels of reduced glutathione in the intracellular fluids than in the plasma may provide an indication of an overall lower oxidation condition within the cells. However, it is interesting to note that intracellular fluids have relatively high concentrations of dissolved sulfate (Table 4), in spite of the more reduced conditions inferred to be present. 

The result is redox cycling which produces active oxygen species which can deplete NADPH and glutathione and potentially cause peroxidation of membrane lipids. 

From the equilibrium constant with glutathione and the standard redox potential of the GSSG/GSH pair, the redox potential of DsbA can be calculated. The redox potential of DsbA is —120 mV, making it the most oxidizing disulfide bond known. For comparison, the redox potential of thioredoxin is —270 mV, and therefore much more reducing. 

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