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ID: 201842 • Letter: P
Question
Please type answer instead of hand writing for me to be able to read. Thanks!
The oxidation of malate by standard conditions (AG"-+30.0 kJ/mol). NAD' to form oxaloacetate is a highly endergonic reaction under a) Calculate the equilibrium constant for the reaction at 25 °C. b) The measured concentration of L-malate in rat liver mitochondria is about 0.2 mM when NAD /INADH] is 10. Calculate the concentration of oxaloacetate at pH 7 in these mitochondria. 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 m. c)Explanation / Answer
A. G° = –RT ln K
30000 = - [8.314 X 298 X ln K]
ln k = -30000 / 2477
ln k = - 12.11
k = e- 12.11
k = 5.5X10-6
B. Malate + NAD+ ------------- Oxaloacetate + NADH G° = +30 kj/mol
k = [Oxaloacetate] [ NADH ] / [Malate] [NAD+]
5.5X10-6 = [Oxaloacetate] [ NADH ] / [Malate] [NAD+]
[Oxaloacetate] = 5.5X10-6 X [Malate] [NAD+] / [ NADH ] [NAD+] / [ NADH ] = 10
= 5.5X10-6 X [0.2 X 10-3 M] 10
= 110 x 10-9
= 0.11 X 10-6M
C. Molarity = No. of molecules /NA X V
N is the number of molecules present in the volume V ; NA is the Avagadro number.
N = 6.022×1023 X 0.11 X 10-6 X V
V = 4/3 X pi X r3
= 4.188 X 10-18
N = 6.022×1023 X 0.11 X 10-6 X 4.188 X 10-18
= 2.76 X 10-1
= 0.276 molecules