The Role of Oxaloacetate in the Cystic Acid Cycle

In vitro, in a lab dish, the enzyme can easily run backwards to decarboxylate oxaloacetate. In 1963, researchers had shown that pyruvacarboxylase can carboxylate other molecules. Oxaloacetate is present in human plasma at concentrations between 20 to 40 micromoles per liter. At these concentrations, experiments suggest that should freely enter liver and muscle cells where it would inhibit pyruvated carboxylase along with at least two other enzymes of pyruvate metabolism.