Acetoacetate Decarboxylase - Activity in Humans and Mammals

Activity in Humans and Mammals

While this enzyme has not been purified from human tissue, the activity was shown to be present in human blood serum.

In humans and other mammals, the conversion of acetoacetate into acetone and carbon dioxide by acetoacetate decarboxylase is a final irreversible step in the ketone-body pathway that supplies the body with a secondary source of energy. In the liver, acetyl co-A formed from fats and lipids are transformed into three ketone bodies: acetone, acetoacetate, and D-β-hydroxybutyrate. Acetoacetate and D-β-hydroxybutyrate are exported to non-hepatic tissues, where they are converted back into acetyl-coA and used for fuel. Acetone and carbon dioxide on the other hand are exhaled, and not allowed to accumulate under normal conditions.

Acetoacetate and D-β-hydroxybutyrate freely interconvert through the action of D-β-hydroxybutyrate dehydrogenase. Subsequently, one function of acetoacetate decarboxylase may be to regulate the concentrations of the other, two 4-carbon ketone bodies.