1. The citric acid cycle ends with the reaction catalyzed by malate dehydrogenase (MDH) shown below. The product of this reaction, oxaloacetate (OAA), combines with acetylCoA (catalyzed by citrate synthase) to begin the cycle. Given this answer the following questions. All of your work must be shown. R = 8.314 J mol-1 K -1| Malate + NAD* OAA + NADH a. What is the keq of the reaction given that AG" = 30.0 kJ/mol? Assume T = 298K. Please show your work. b. The concentration of malate within a rat mitochondria is about 0.20mM. Furthermore, the ratio of [NAD+]/[NADH] is around 10/1. Given this calculate the concentration of OAA within the mitochondria considering that the MDH reaction is at equilibrium under mitochondrial conditions. c. Citrate synthase catalyzes the first step in the CAC as shown below. Determination of its actual free energy change is difficult for a number of reasons however most scientist will point to the fact that it is negative. Let's assume AG = -5.0 kJ/mol. The standard free energy change for this reaction is easily determined and is AG"* = - 32.2 kJ/mol. The reason it is so exergonic is due to the energy stored in the thioester bond of acetyl-CoA. Given the assumed actual free energy value of citrate synthase, calculate the concentration of acetyl-CoA if citrate concentration were 0.45mM and CoA concentration were 2.0mm within the mitochondria. Please use the OAA concentration you obtained from your answer to b. In this case T = 310K. OAA + Acetyl-CoA = Citrate + CoA d. Let's do the same calculation as in c. but let's assume there is less energy in the thioester bond of acetyl CoA leading to a standard free energy change of AG" = -10 kJ/mol. What will be the acetyl-CoA concentration in the mitochondria given this new standard free energy change assuming the actual free energy remains at a modest AG = -5.0 kJ/mol? Is this a reasonable cellular concentration of acetyl-CoA? Given this discuss why it is important that energy be stored within the thioester bond of acetyl-CoA.

1. The citric acid cycle ends with the reaction catalyzed by malate dehydrogenase (MDH) shown below. The product of this reaction, oxaloacetate (OAA), combines with acetylCoA (catalyzed by citrate synthase) to begin the cycle. Given this answer the following questions. All of your work must be shown. R = 8.314 J mol-1 K -1| Malate + NAD* OAA + NADH a. What is the keq of the reaction given that AG" = 30.0 kJ/mol? Assume T = 298K. Please show your work. b. The concentration of malate within a rat mitochondria is about 0.20mM. Furthermore, the ratio of [NAD+]/[NADH] is around 10/1. Given this calculate the concentration of OAA within the mitochondria considering that the MDH reaction is at equilibrium under mitochondrial conditions. c. Citrate synthase catalyzes the first step in the CAC as shown below. Determination of its actual free energy change is difficult for a number of reasons however most scientist will point to the fact that it is negative. Let's assume AG = -5.0 kJ/mol. The standard free energy change for this reaction is easily determined and is AG"* = - 32.2 kJ/mol. The reason it is so exergonic is due to the energy stored in the thioester bond of acetyl-CoA. Given the assumed actual free energy value of citrate synthase, calculate the concentration of acetyl-CoA if citrate concentration were 0.45mM and CoA concentration were 2.0mm within the mitochondria. Please use the OAA concentration you obtained from your answer to b. In this case T = 310K. OAA + Acetyl-CoA = Citrate + CoA d. Let's do the same calculation as in c. but let's assume there is less energy in the thioester bond of acetyl CoA leading to a standard free energy change of AG" = -10 kJ/mol. What will be the acetyl-CoA concentration in the mitochondria given this new standard free energy change assuming the actual free energy remains at a modest AG = -5.0 kJ/mol? Is this a reasonable cellular concentration of acetyl-CoA? Given this discuss why it is important that energy be stored within the thioester bond of acetyl-CoA.

Biochemistry

6th Edition

ISBN:9781305577206

Author:Reginald H. Garrett, Charles M. Grisham

Publisher:Reginald H. Garrett, Charles M. Grisham

Chapter18: Glycolysis

Section: Chapter Questions

Problem 24P: Based on your knowledge of the structure of NAD+ and an assumption that coenzyme dissociation is the...

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