Question

Use the half reaction reduction potentials found on Table 14-4 to calculate the standard state Gibb’s Free Energy (ΔG°') for the reaction:

Pyruvate + NADH + H+ <> Lactate + NAD+

If the steady state cellular concentrations of Pyruvate and Lactate are held fixed at 0.051 mM and 0.51 mM, respectively, then what is the ratio of [NAD+]/[NADH] below which this reaction begins to be energetically favorable at 37°C?

here is the table:

TABLE 14-4 Standard Reduction Potentials of Some Biochemically Important Half-Reactions on HGO 2 e 0.815 NO NO H, O 0.42 Cytochrome a (Fes e cytochrome as (Fe2+) 0.385 O, H,O 0.295 Cytochrome a (Fest) e me a (Fe 1) 0.29 Cytochrome c (Fes*) e cytochrome c (Fe2+) 0.235 Cytochrome c (Fest) e cytochrome c (Fe2+) 0.22 Cytochrome b (Fest) e cytochrome b (Fe (mitochondrial 0.077 Ubiquinone ubiquinol. 0.045 Fumarate 2 H 2 e succinate 0.031 FAD 2 H+ 2 e FADH2 (in flavoproteins 0.040 oxaloacetate 2 H 2 e malate 0.166 Pyruvate 2 H+ 2 e lactate 0.185 Acetaldehyde 2 H 2 e thanol 0.197 FAD 2 H+ 2 e FADH2 (free coenzyme) 0.219 H,S 0.23 Lipoic acid 2 H 2 e dihydrolipoic acid 0.29 NAD H 2 e NADH 0.315 NADP H+ 2 e NADPH 0.320 Cysteine disulfide 2 H 2 e 2 cysteine 0.340 Acetoacetate 2 H+ 2 e B-hydroxy butyrate 0.346 H e 0.421 SO H2O 0.515 Acetate 3 H 2 e acetaldehyde H20 0.581