From E°′ values in Table 14.1, calculate the equilibrium constant for the glutathione peroxidase reaction at 37 °C.

Table 14.1

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TABLE 14.1 Standard reduction potentials of interest in biochemistry Oxidant Acetate + CO₂ + 2H+ + 2e¯ Succinate + CO₂ + 2H+ + 2e- Acetate + 3H+ + 2e¯ Ferredoxin (oxidized) + e 2H+ + 2e a-Ketoglutarate + CO₂ + 2H+ + 2e¯ Acetoacetate + 2H+ + 2e™ Pyruvate + CO₂ + H+ + 2e™ NAD+ + H+ + 2e™ NADP+ + H+ + 2e Lipoate (oxidized) + 2H+ + 2e- 1,3-Bisphosphoglycerate + 2H+ + 2e™ Glutathione (oxidized) + 2H+ + 2e FAD (free coenzyme) +2H+ + 2e™ Acetaldehyde + 2H+ + 2e Pyruvate + 2H+ + 2e Oxaloacetate + 2H+ + 2e O₂ + e a-Ketoglutarate + NH + 2H+ + 2e FAD (enzyme-bound) + 2H+ + 2e™ Methylene blue (oxidized) + 2H+ + 2e Fumarate + 2H+ + 2e¯ Q + 2H+ + 2e™ Dehydroascorbate + 2H+ + 2e Cytochrome b (+3) + e Cytochrome c₁ (+3) + e Cytochrome c (+3) + e Cytochrome a (+3) + e 0₂ + 2H+ + 2e™ Ferricyanide + 2e™ NO3 (Nitrate) + 2H+ + 2e Cytochrome ag(+3) + e Fe (+3) + e ¹0₂ + 2H+ + 2e = Reductant Pyruvate + H₂O a-ketoglutarate + H₂O Acetaldehyde + H₂O Ferredoxin (reduced) H₂ Isocitrate B-Hydroxybutyrate Malate NADH NADPH Lipoate (reduced) Glyceraldehyde-3-phosphate + P₁ 2 Glutathione (reduced) FADH₂ Ethanol Lactate Malate O₂ (superoxide) Glutamate + H₂O FADH₂ (enzyme-bound) Methylene blue (reduced) Succinate QH₂ Ascorbate Cytochrome b (+2) Cytochrome c₁ (+2) Cytochrome c (+2) Cytochrome a (+2) H₂O₂ Ferrocyanide NO₂ (Nitrite) + H₂O Cytochrome a3 (+2) Fe(+2) H₂O n 2 2 2 1 2 NN 2 2 2 2 2 2 2 NN 2 2 2 2 2 1 2 2 2 2 2 2 1 1 1 1 2 2 2 1 1 2 E° (V) -0.70 -0.67 -0.60 -0.43 -0.42 -0.38 -0.35 -0.33 -0.32 -0.32 -0.29 -0.29 -0.23 -0.22 -0.20 -0.19 -0.17 -0.16 -0.14 -0 to -0.30 0.01 0.03 0.04 0.06 0.07 0.23 0.25 0.29 0.30 0.36 0.42 0.55 0.77 0.82