ornithine aminotransferase

or·ni·thine ami·no·trans·fer·ase (orґnĭ-thēn ə-me″no-transґfər-ās) an enzyme of the transferase class that catalyzes the conversion of ornithine to Δ¹-pyrroline 5-carboxylate via transfer of the ornithine amino group to an α-keto acid (e.g., α-ketoglutarate). The reaction is important in the degradation of ornithine from excess dietary tissue arginine, in the biosynthesis of proline, and in the de novo synthesis of ornithine. The enzyme is a mitochondrial matrix protein occurring in most cells; deficiency of it, an autosomal recessive trait, causes gyrate atrophy of choroid and retina. Abbreviated OAT. In EC nomenclature called ornithine–oxo-acid transaminase.