Reduction Potentials in the Electron Transport ChainRECALL Why are all the reactions in Ta...

Reduction Half Reaction

E°'(V)

O2 + 2H+ + 2e− H2O

0.816

Fe3+ + e2 → Fe2+

0.771

Cytochrome a3(Fe3+) + e2 → Cytochrome a3(Fe2+)

0.350

Cytochrome a(Fe3+) + e2 → Cytochrome a(Fe2+)

0.290

Cytochrome c(Fe3+) + e2 → Cytochrome c(Fe2+)

0.254

Cytochrome c1(Fe3+) + e2 → Cytochrome c1(Fe2+)

0.220

CoQH• + H+ + e− → CoQH2 (coenzyme Q)

0.190

CoQ + 2H+ + 2e− → CoQH2

0.060

Cytochrome bH(Fe3+) + e− → Cytochrome bH(Fe2+)

0.050

Fumarate + 2H+ + 2e− → Succinate

0.031

CoQ + H+ + e− → CoQH•

0.030

[FAD] + 2H+ + 2e− → [FADH2]

0.003−0.091*

Cytochrome bL(Fe3+) + e− → Cytochrome bL(Fe2+)

−0.100

Oxaloacetate + 2H+ + 2e− → Malate

−0.166

Pyruvate + 2H+ + 2e− → Lactate

−0.185

Acetaldehyde + 2H+ + 2e− → Ethanol

−0.197

FMN + 2H+ + 2e− → FMNH2

−0.219

FAD + 2H+ + 2e− → FADH2

−0.219

1,3-bisphosphoglycerate + 2H+ + 2e− → Glyceraldehyde-3-phosphate + Pi

−0.290

NAD+ + 2H+ + 2e− → NADH + H+

−0.320

NADP+ + 2H+ + 2e− NADPH + H+

−0.320

α-Ketoglutarate + CO2 +2H+ + 2e− → Isocitrate

−0.380

Succinate + CO2 + 2H+ + 2e− → α-Ketoglutarate + H2O

−0.670

*Typical values for reduction of bound FAD in flavoproteins such as succinate dehydrogenase. Note that we have shown a number of components of the electron transport chain individually. We are going to see them again as part of complexes. We have also included values for a number of reactions we saw in earlier chapters.