Fumarase is an enzyme that catalyze the reversible hydration/dehydration of fumarate to S-malate and is involved in the tricarboxylic acid or Krebs cycle. Fumarase exists in both form, cytosolic formand N-terminal extend mitochondrial form. The N-terminal extended form is targeted to the mitochondrion, where the removal of the extension is the same form as in the cytoplasm. Fumarase is thought to act as a tumor suppressor, which deficiency can lead to progressive encephalopathy, cerebral atrophy and development delay.