Equilibrium constants of the malate dehydrogenase, citrate synthase, citrate lyase, and acetyl coenzyme A hydrolysis reactions under physiological conditions.

The observed equilibrium constants (Kobs) of the malate dehydrogenase (EC 1.1.1.37), citrate synthase (EC 4.1.3.7) and citrate lyase (EC 4.1.3.6) reactions have been determined under near physiological conditions (38”, pH 7.0, Z = 0.25, free [Mg”+] = 10u3 M). From these values the observed standard free energy change (AGibs) for the hydrolysis of acetyl-CoA has been determined. Under the above conditions, and taking the standard state of liquid water to have activity = unity ([Hz01 = l), the equilibrium constants of the three reactions at pH 7.0 may be written: Malate dehydrogenase