Here are four problems (5 pts each) involving the calculation of D G °\' for met
ID: 1068703 • Letter: H
Question
Here are four problems (5 pts each) involving the calculation of DG°' for metabolic reactions we have discussed, based on experimentally determined redox potentials. Calculate the DG°' for each reaction using the equation DG°' = -nFDE0' and the values for E0' given in Table 1. Show your work and circle your answer.
Table 1. Reduction potentials for reduction half reactions:
1/2 O2 + 2H+ + 2e- ® H2O E0' = +0.82 V
fumarate + 2H+ + 2e- ® succinate E0' = +0.03 V
oxaloacetate + 2H+ + 2e- ® malate E0' = -0.17 V
pyruvate + 2H+ + 2e- ® lactate E0' = -0.19 V
a-ketoglutarate + CO2 + 2H+ + 2e- ® isocitrate E0' = -0.38 V
FAD + 2H+ + 2e- ® FADH2 E0' = -0.22 V
NAD+ + 2H+ + 2e- ® NADH + H+ E0' = -0.32 V
CoQ + 2H+ + 2e- ® CoQH2 E0' = +0.06 V
Problem 3. malate + NAD+ ® oxaloacetate + NADH + H+
Problem 4. FADH2 + CoQ ® FAD + CoQH2
Explanation / Answer
malate + NAD+ -------------------> oxaloacetate + NADH + H+
malate -----------------> oxaloacetate + 2H+ + 2e- E0 = 0.17V
NAD+ + 2H+ + 2e- ---------> NADH + H+ E0' = -0.32 V
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malate + NAD+ -------------------> oxaloacetate + NADH + H+ E0cell= -0.15V
DG°' = -nFDE0'
= -2*96500*-0.15 = 28950J
FADH2 + CoQ ------------> FAD + CoQH2
FADH2 ------------> FAD + 2H+ + 2e- E0 = 0.22V
CoQ + 2H+ + 2e- -----------> CoQH2 E0' = +0.06 V
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FADH2 + CoQ ------------> FAD + CoQH2 E0cell =0.28V
DG°' = -nFDE0'
= -2*96500*0.28 = -54040J
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