Ornithine Aminotransferase

Ornithine aminotransferase is an enzyme involved in the ultimate formation of proline from ornithine. Ornithine aminotransferase forms the initial intermediate in this process. It catalyzes the reverse reaction as well, and is therefore essential in creating ornithine from the starting substrate proline. Glutamate acts as the amine donor for ornithine aminotransferase, forming α-ketoglutarate. In the reverse direction, α-ketoglutarate accepts the amine group, forming glutamate and leading to the ultimate conversion of proline to ornithine. A deficiency of this enzyme causes ornithine aminotransferase deficiency, also known as gyrate atrophy of choroid and retina.

Ornithine aminotransferase catalyzes the following reaction:

• L-ornithine + a 2-oxo acid = L-glutamate 5-semialdehyde + an L-amino acid