Table 1.
Standard Reduction Potentials (E°′) of Representative Redox Couples
| Redox couples | E°′/mV at 25°C | Reduction types | Oxidizing ability |
|---|---|---|---|
| NAD+, H+/NADH | −316 | Two-electron reduction | Low High |
| NADP+, H+/NADPH | −315 | ||
| GSSG, 2H+/2GSH | −240 | ||
| Trx-S2, 2H+/Trx-(SH)2 | −240 | ||
| Cys-S-S-Cys, 2H+/2Cys-SH | −230 | ||
| FMN, 2H+/FMNH2 | −219 | ||
| FAD, 2H+/FADH2 | −219 | ||
| Grx-S2, 2H+/Grx-(SH)2 | −218 | ||
| Acetaldehyde, 2H+/alcohol | −197 | ||
| Pyruvate, 2H+/lactate | −183 | ||
| Oxaloacetate, 2H+/malate | −166 | ||
| 2H3O++2e−/H2(g), 2H2O | 0 | ||
| Ubiquinone, 2H+/ubihydroquinone | +84 | ||
| Ascorbate•−, H+/ascorbate | +282 | One-electron reduction | |
| O2, 2H+/H2O2 | +300 | ||
| H2O2, 2H+/H2O, HO• | +320 | ||
| α-Tocopheroxyl•, H+/vitamin E | +500 | ||
| RS•/RS− (thiolate) | +920 | ||
| O2•−, 2H+/H2O2 | +940 | ||
| ROO•, H+/ROOH (alkylperoxyl radical) | +1000 | ||
| RO•, H+/ROH (aliphatic alkoxyl radical) | +1600 | ||
| HO•, H+/H2O | +2310 |
Adapted from Schafer and Buettner (89) with permission.
GSH, glutathione; Grx, glutaredoxin; GSSG, GSH disulfide; H2O2, hydrogen peroxide; NAD+, nicotinamide adenine dinucleotide; NADH, reduced NAD+; NADP+, phosphorylated NAD+; NADPH, reduced NADP+; O2•−, superoxide anion; Trx, thioredoxin.