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In the last reaction of the citric acid cycle, malate dehydrogenation regenerates the oxaloacetate necessary for the entry of acetyl-CoA into the cycle. L-Malate + NAD+ →→→ oxaloacetate + NADH + H+ AG'° 30.0 kJ/mol Calculate the equilibrium constant for this reaction at 25 °C. 4.5 x10-6 K'eq = Incorrect Because AG'° assumes a standard pH of 7, the calculated equilibrium constant corresponds to [oxaloacetate] [NADH] K'eq = [L-malate] [NAD+] [NAD+] The measured concentration of L-malate in rat liver mitochondria is about 0.20 mM when [NADH] is 10.
Calculate the concentration of oxaloacetate at pH 7 in these mitochondria. 9.0 X10-⁹ [oxaloacetate] = M Incorrect To appreciate the magnitude of mitochondrial oxaloacetate concentration, calculate the number of oxaloacetate molecules in a single rat liver mitochondrion. Assume the mitochondrion is a sphere with a diameter of 2 µm. 23 Noxaloacetate = molecules Incorrect