Standard Reduction Potentials (E0'), 25oC

oxidant

reductant

n (electrons)

Eo� (volts)

Acetate + carbon dioxide

pyruvate

2

-0.70

succinate + CO2 + 2H+

α−ketoglutarate + H2O

 2

-0.67

acetate

acetaldehyde

2

-0.60
glycerate-3-P glyceraldehyde-3-P + H2O 2 -0.55
O2 O2- 1 -0.45
ferredoxin (ox) ferredoxin (red) 1 -0.43

Carbon dioxide

formate

2

-0.42

2H+

H2

2

-0.42

α-ketoglutarate + CO2 + 2H+

isocitrate

 2

-0.38
acetoacetate β-hydroxybutyrate 2 -0.35

Cystine

cysteine

2

-0.34

Pyruvate + CO2

malate

2

-0.33

NAD+ + 2H+

NADH  + H+

 2

-0.32

NADP+ + 2H+

NADPH  + H+

 2

-0.32
FMN (enzyme bound) FMNH2 2 -0.30

Lipoic acid, ox

Lipoic acid, red

 2

-0.29

1,3 bisphosphoglycerate + 2H+

glyceraldehyde-3-P + Pi

 2

-0.29

Glutathione, ox

red

2

-0.23

FAD (free) + 2H+

FADH2

 2

-0.22

Acetaldehyde + 2H+

ethanol

2

-0.20

Pyruvate + 2H+

lactate

 2

-0.19

Oxalacetate + 2H+

malate

2

-0.17

α-ketoglutarate + NH4+ 

glutamate

2

-0.14

FAD + 2H+ (bound)

FADH2 (bound)

 2

0.003-0.09

Methylene blue, ox

Methylene blue, red

2

0.01

Fumarate + 2H+

succinate

2

0.03

CoQ (Ubiquinone - UQ + H+ UQH. 1 0.031
UQ + 2H+ UQH2 2 0.06

Dehydroascorbic acid

ascorbic acid

2

0.06

Ubiquinone; ox

red

2

0.10

Cytochrome b2; Fe3+

Cytochrome b2; Fe2+

 1

0.12

Cytochrome c1; Fe3+

Cytochrome c1; Fe2+

 1

0.22

Cytochrome c; Fe3+

Cytochrome c; Fe2+

 1

0.25

Cytochrome a; Fe3+

Cytochrome a; Fe2+

 1

0.29

1/2 O2 + H2O

H2O2

2

0.30

Cytochrome a3; Fe3+

Cytochrome a3; Fe2+

 1

0.35

Ferricyanide

ferrocyanide

2

0.36

Cytochrome f; Fe3+

Cytochrome f; Fe2+

 1

0.37

Nitrate

nitrite

1

0.42

Photosystem P700 . . 0.43

Fe3+

Fe2+

 1

0.77

1/2 O2 + 2H+

H2O

 2

0.816