Biochemistry
6th Edition
ISBN: 9781305577206
Author: Reginald H. Garrett, Charles M. Grisham
Publisher: Cengage Learning
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Question
Chapter 20, Problem 7P
Interpretation Introduction
To propose:
The succinate dehydrogenase reaction.
Introduction:
Out of the dehydrogenase reactions in the glycolysis and the TCA cycle, all but one-use NAD+ as the electron acceptor.
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All dehydrogenases of glycolysis and the TCA cycle use NAD* (E° for NAD*/NADH
is -0.32V) as electron acceptor except succinate dehydrogenase (which uses FAD (E° for
FAD/FADH2 is 0.05V).
Based on AG° = -NFEº, show and state (1-2 sentences) why is FAD a more appropriate
electron acceptor than NAD* in the dehydrogenation of succinate (consider the E° values of
%3D
Uptake in Na+
Vmax
Uptake in absence of Na+
Vmax
substrate
K: (mM)
Kt (mM)
L-leucine
420
0.24
23
0.2
D-Leucine
310
4.7
5
4.7
L-valine
225
0.31
19
0.31
fumarate/succinate (E° = 0.031), NAD*/NADH, and the succinate dehydrogenase
FAD/FADH2).
Based on the action of thiamine pyrophosphate in catalysis of the pyruvate dehydrogenase reaction, suggest a suitable mechanism for the fourth step in the pyruvate decarboxylase reaction in yeast:
For 30 moles of glucose that is completely oxidized in the glycolysis down to the Krebs cycle, what is the total moles of ATP produced in a cell with an ATP synthase possessing 8 c subunits? Assume that the malate aspartate shuttle is used for NADH transport.
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- Using the ActiveModel for enoyl-CoA dehydratase, give an example of a case in which conserved residues in slightly different positions can change the catalytic rate of reaction.arrow_forward(a) Consider the oxidation of malate to oxaloacetate by NAD*: malate + NAD+ → oxaloacetate + NADH + H+ In yeast mitochondria, where the pH = 8.1, this reaction is exergonic only at low oxaloacetate concentrations. Assuming a pH = 8.1, a temperature of 37 °C, and the steady-state concentrations given below, calculate the maximum concentration of oxaloacetate at which the reaction will still be exergonic. malate + NAD*→ oxaloacetate + NADH + H* lactate + NAD →→ pyruvate + NADH + H+ half reaction Pyruvate + 2H+ + 2e → lactate Pyruvate + CO₂ + H + 2e → malate Intracellular steady state concentrations: malate = 410 μM; NAD = 20.0 mM; pyruvate = 3.22 mM; NADH = 290 μM; AG=+29.7 kJ/mol AG¹ = +25.1 kJ/mol E° (V) - 0.190 - 0.330 lactate 1.1 mM CO₂ = 15.5 torrarrow_forwardThe reaction catalyzed by malate dehydrogenase has a ΔG°′ value of +29.7 kJ⋅mol−1. Given what this says about the occurrence of the reaction catalyzed by malate dehydrogenase in cells explain how the reaction catalyzed by citrate synthase (−31.5 kJ⋅mol−1) influences that activity of malate dehydrogenase. In addition, explain how the activity of citrate synthase functions as a regulatory point for the citric acid cyclearrow_forward
- All the dehydrogenases of glycolysis and the citric acid cycle use NAD+ (E°' for NAD+/NADH is -0.32 V) as the electron acceptor, except succinate dehydrogenase, which uses covalently bound FAD (E°' for FAD/FADH2 is +0.050 V). Suggest why FAD is a more appropriate electron acceptor than NAD+ in the dehydrogenation of succinate, based on the E°' values of fumarate/succinate (E°' = +0.031 V)arrow_forwardBegining with 1 M concentrations of each reactant and product at pH=7 and 25.0 degrees C, calculate the K'eq of the reaction Pyruvate + NADH <=> Lactate + NADH+H+.Note the temperature of this reaction will not affect the standard reducton potential delta E'o in the table 13-7b.arrow_forwardCompare the delta ΔG0' values for the oxidation of succinate by NAD+ and by FAD. Use the data given in Table 18.1 to find the E0' of the NAD+-NADH and fumarate-succinate couples, and assume that E0' for the FAD – FADH2 redox couple is nearly 0.05 V. Why is FAD rather than NAD+ the electron acceptor in the reaction catalyzed by succinate dehydrogenase?arrow_forward
- Begining with 1 M concentrations of each reactant and product at pH=7 and 25.0 degrees C, calculate the K'eq of the reaction Pyruvate + NADH Lactate + NADH+H+. Note the temperature of this reaction will not affect the standard reducton potentialarrow_forwardAll the dehydrogenases of glycolysis and the citric acid cycle use NAD+ (?′°E′° for NAD+/NADH is −0.32 V−0.32 V) as electron acceptor except succinate dehydrogenase, which uses covalently‑bound FAD (?′°E′° for FAD/FADH2 in this enzyme is 0.050 V).0.050 V). The ?′°E′° value for fumarate/succinate is 0.031 V.0.031 V. a)Calculate the Δ?′°ΔG′° value for the oxidation of succinate using NAD+. b)Calculate the Δ?′°ΔG′° value for the oxidation of succinate using covalently‑bound FAD.arrow_forwardBegining with 1 M concentrations of each reactant and product at pH=7 and 25.0 degrees C, calculate the K'eq (to one decimal point) of the reaction Pyruvate + NADH+H+ <=> Lactate + NAD+.Note the temperature of this reaction will not affect the standard reducton potential delta E'o in the table 13-7b. please provide a comprehensive explanation with each step taken.arrow_forward
- For lactate dehydrogenase reaction if km for NADH is 2×10^-4 M . What concentration of it would be appropriate for determining Km for pyruvate?arrow_forwardConsider one of the reactions of the citric acid cycle shown below Malate + NAD+ ⇆ Oxaloacetate + NADH + H+ (malate dehydrogenase) ΔG˚′ = +29.7 kJ/mol. Describe two factors that allow this thermodynamically unfavorable reaction to occur in the direction of malate to oxaloacetate.arrow_forwardThe standard reduction potential for ubiquione (A or coenzyme Q) is .045 V, and the standard reduciton potential (E) for FAD is -0.219 V. Using these values, show that the oxidation for FADH2 by ubiquinone theoretically liberates enough energy to drive the synthesis of ATP. Faraday constant =96.48KJ/Vol delta G' standard for ATP Synthesis is +30.5 KJ/mol R=8.314 J/mol K=1.987 cal/mol Karrow_forward
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