Wheeler and Mathews (J.Biol.Chem.286:16992-16996,2011) reported the concentrations of adenine nucleotides in rat liver mitochondria as follows: ATP, 5.5 mM; ADP, 5.1 mM; AMP, 1.8 mM.
(a) Calculate the adenylate energy charge within the mitochondrion.
(b) Most measurements of adenylate energy charge in whole cells or cytosol give values close to 0.9. Speculate on reasons why it might be advantageous for mitochondria to have an ADP concentration almost as high as that of ATP.
(c) succinyl-CoA + ADP + Pi → succinate + ATP + CoA-SHΔG°′ = - 2.9 kJ/mol
If [Pi] within the mitochondrion is 0.05 M and succinate and succinyl-CoA are present at equimolar concentrations, what is the maximum mitochondrial concentration of CoA-SH at which the reaction can be exergonic?