2. Formation of OAA in mitochondria. In the last reaction of the TCA cycle, malate is dehydrogenated toregenerate the OAA necessary for the entry of acetyl-coA into the cycle:L-Malate + NAD+ → OAA + NADH + H+AGo = 30.0 kJ/mol(a) Calculate the equilibrium ponstant for this reaction at 25 C.b) Because AGo assumes a standard pH of 7, the equilibrium constant calculated in (a) corresponds toK'eg_JOAA][NADH][L-malate][NAD*]The measured concentration of L-malate in rat liver mitochondria is about 0.2 mM when the ratio[NAD*] / [NADH] is 10. Calculate the concentration of OAA at pH 7 in these mitochondria.(c) To appreciate the magnitude of the mitochondrial OAA concentration, calculate the number of OAAmolecules in a single rat liver mitochondrion. Assume the mitochondrion is a sphere of diameter 2.0 µm.(From problem 10, chapter 16)

Free energy change for a reaction, ΔG, can be solved using the standard change in Gibbs free energy,…

2. Formation of OAA in mitochondria. In the last reaction of the TCA cycle, malate is dehydrogenated to regenerate the OAA necessary for the entry of acetyl-coA into the cycle: L-Malate + NAD+ → OAA + NADH + H+ AGO' = 30.0 kJ/mol (a) Calculate the equilibrium konstant for this reaction at 25 C. b) Because AG assumes a standard pH of 7, the equilibrium constant calculated in (a) corresponds to [OAA][NADH]_ [L-malate][NAD*] K'eq = The measured concentration of L-malate in rat liver mitochondria is about 0.2 mM when the ratio [NAD*] / [NADH] is 10. Calculate the concentration of OAA at pH 7 in these mitochondria. (c) To appreciate the magnitude of the mitochondrial OAA concentration, calculate the number of OAA

2. Formation of OAA in mitochondria. In the last reaction of the TCA cycle, malate is dehydrogenated to regenerate the OAA necessary for the entry of acetyl-coA into the cycle: L-Malate + NAD+ → OAA + NADH + H+ AGO' = 30.0 kJ/mol (a) Calculate the equilibrium konstant for this reaction at 25 C. b) Because AG assumes a standard pH of 7, the equilibrium constant calculated in (a) corresponds to [OAA][NADH]_ [L-malate][NAD] K'eq = The measured concentration of L-malate in rat liver mitochondria is about 0.2 mM when the ratio [NAD] / [NADH] is 10. Calculate the concentration of OAA at pH 7 in these mitochondria. (c) To appreciate the magnitude of the mitochondrial OAA concentration, calculate the number of OAA

Biochemistry

6th Edition

ISBN:9781305577206

Author:Reginald H. Garrett, Charles M. Grisham

Publisher:Reginald H. Garrett, Charles M. Grisham

Chapter20: Electron Transport And Oxidative Phosphorylation

Section: Chapter Questions

Problem 11P

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(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 torr
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Consider 3 molecules of galactose: (write only the whole number; no decimal places) How many turns of Krebs Cycle will these molecules undergo for complete oxidation? b. How many moles of ATP are produced upon complete oxidation via malate-aspartate shuttle? c. If all the galactose molecules oxidize via pentose phosphate pathway (oxidative stage only), how many moles of NADPH will be produced?
Aconitase catalyzes the reaction: citrate ↔ HisocitrateThe standard free energy change, ΔG°′, for this reaction is +6.3 kJ/mol.However, the observed free energy change (ΔG) for this reaction in mammalian mitochondria at 25°C is ∼0 kJ>mol (Table 13.2).(a) Calculate the ratio of [isocitrate]>[citrate] in mitochondria.(b) Is this reaction likely to be a control point for the citric acid cycle? Whyor why not?
Chambers and coworkers have reported [NAD+] and [NADH] concentrations in yeast mitochondria as 20 mM and 0.3 mM, respectively. Consider the Malate Dehydrogenase reaction below: Malate + NAD+ → Oxaloacetate + NADH + H+ ∆G0’ = +29.7 kJ/mol If Malate concentration in yeast mitochondria is 0.4 mM what is the maximum concentration of oxaloacetate needed to make the reaction exergonic at pH 7.0 and 370C?
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The following incorrect description of the HMS path is () A, 6-P-glucose can be converted into pentose phosphate through this pathway B. Four-carbon and seven-carbon sugars can be provided through this route C. For every mole of carbon dioxide produced when 6-P-glucose is converted to pentose phosphate, it also produces 1 mole of NADPH D, 6-P-glucose is decomposed in this way without consumption of ATP Among the following enzyme-catalyzed reactions that can generate substrate level phosphorylation to generate GTP are () A, hexokinase B, enolase C, succinate thiokinase D, succinate dehydrogenase The limiting factor of fatty acid synthesis in cell fluid is (). A, condensation enzyme B, hydration enzyme C, lipoacyl group transferase D, acetyl-CoA carboxylase Which of the following amino acids is an essential amino acid? () A.Thr B.Lys C.Met D.Arg
All 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?′°Δ⁢G′° value for the oxidation of succinate using NAD+. b)Calculate the Δ?′°Δ⁢G′° value for the oxidation of succinate using covalently‑bound FAD.
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Citrate synthase catalyzes the reaction Oxaloacetate + acetyl-CoA →citrate + HS-CoA The standard free energy change for the reaction is −31.5 kJ · mol−1. (a) Calculate the equilibrium constant for this reaction at 37°C. (b) Would you expect this reaction to serve as a control point for its pathway (the citric acid cycle)?