Biochemists consider the citric acid cycle to be the cen-tral reaction sequence in metabolism. One of the key steps isan oxidation catalyzed by the enzyme isocitrate dehydrogenaseand the oxidizing agent NAD. Under certain conditions, thereaction in yeast obeys 11th-order kinetics Rate=k[enzyme][isocitrate]⁴[AMP]²[NAD⁺]m[Mg²⁺]² What is the order with respect to NAD⁺?

Biochemists consider the citric acid cycle to be the cen-tral reaction sequence in metabolism. One of the key steps isan oxidation catalyzed by the enzyme isocitrate dehydrogenaseand the oxidizing agent NAD. Under certain conditions, thereaction in yeast obeys 11th-order kinetics Rate=k[enzyme][isocitrate]⁴[AMP]²[NAD⁺]m[Mg²⁺]² What is the order with respect to NAD⁺?

Biochemistry

6th Edition

ISBN:9781305577206

Author:Reginald H. Garrett, Charles M. Grisham

Publisher:Reginald H. Garrett, Charles M. Grisham

Chapter27: Metabolic Integration And Organ Specialization

Section: Chapter Questions

Problem 8P: Ethanol as a Source of Metabolic Energy (Integrates with Chapters 19 and 20.) Acetate produced in...

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Ethanol as a Source of Metabolic Energy (Integrates with Chapters 19 and 20.) Acetate produced in ethanol metabolism can be transformed into acetyl-COA by the acetyl thiokinase reaction: Acetate+ATP+CoASHacetyleCoA+AMP+PPiAcetyle-CoA then can enter the citric acid cycle and undergo oxidation to 2 CO2by this route, assuming oxidative phosphorylation is part of the process? (Assume all reactions prior to acetyl-CoA entering the citric acid cycle occur outside the mitochondrion). Per carbon atom, which is a better metabolic fuel, ethanol or glucose? That is, how many ATP equivalents per carbon atom are generated by combustion of glucose versus ethanol to CO2?
Page of 6 ZOOM + name: 3. In the last reaction of the citric acid cycle, malate is dehydrogenated to regenerate the oxaloacetate necessary for the entry of acetyl-CoA into the cycle: L-Malate + NAD+ → oxaloacetate + NADH + H* AG'° = 30.0 kJ/mol (a) Calculate the equilibrium constant for this reaction at 25 °C. (b) Because AG°' assumes a standard pH of 7, the equilibrium constant calculated in (a) corresponds to [oxaloacetate][NADH] Keq [L-malate][NAD*] The measured concentration of L-malate in rat liver mitochondria is about 0.20 mM when [NAD*]/[NADH] is 10. Calculate the concentration of oxaloacetate at pH 7 in these mitochondria. (c) To appreciate the magnitude of the mitochondrial oxaloacetate concentration, calculate the number of oxaloacetate molecules in a single rat liver mitochondrion. Assume the mitochondrion is a sphere of diameter 2.0 microns.
[AktivGrid] Draw the product of the reaction of isocitrate catalyzed by isocitrate dehydrogenase in the TCA (citric acid) cycle. Provide the structure in the protonation state found in physiological conditions. rxn' F-C-H NAD+ isocitra te dehydro genase NADH, Dra H+, > Problem 5 of 12 Submit H Atoms, Bonds and Rings OH Charges CH2OH Drag To Pan CH2OH- H OH Undo Reset ―CH2OH- Remove Done ⚫SH CHO +
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Coupling ATP hydrolysis to glucose phosphorylation makes thermodynamic sense, but consider how the coupling might take place. Given that coupling requires a common intermediate, one conceivable mechanism is to use ATP hydrolysis to raise the intracellular concentration of P,. The increase in P, concentration would drive the unfavorable phosphorylation of glucose by P. Is increasing the P concentration a reasonable way to couple ATP hydrolysis and glucose phosphorylation? No. The phosphate salts of divalent cations would be present in excess and precipitate out. Yes. The extra ATP hydrolysis would provide enough free energy to drive the phosphorylation reaction. Yes. Increasing the concentration of P, would decrease K'e and shift equilibrium to the right. No. The extra P, would give a negative AG, but would give a positive AG. In hepatocytes, the enzyme glucokinase catalyzes the ATP-coupled phosphorylation of glucose. Glucokinase binds both ATP and glucose, forming a glucose-ATP-enzyme…