Thermodynamics of Citrate Synthase Reaction in Cells Citrate is formed by the condensation of acetyl-CoA with oxaloacetate, catalyzed by citrate synthase: Oxaloacetate + acetyl-CoA + HO citrate + CoA + H+ In rat heart mitochondria at pH 7.0 and 25 C, the concentrations of reactants and products are: ox- aloacetate, 1 M; acetyl-CoA, 1 M; citrate, 220 m; and CoA, 65 M. The standard free-energy change for the citrate synthase reaction is -32.2 kJ/mol. What is the direction of metabolite flow through the cit- rate synthase reaction in rat heart cells? Explain.