Ornithine

Ornitina

Ornithine is a dibasic amino acid, synthesized in the cytosol as a product of glutamate. It is formed by acetylation of its amino group, phosphorylation, and reduction of the acetylated derivative to N-acetylglutamic-γ-semialdehyde. Subsequent transamination produces α-N-acetylornithine which, releasing the acetyl group, forms ornithine. It can be incorporated into the urea cycle to form citrulline. In addition, it is the precursor of the polyamine putrescine. It is the biosynthetic precursor and postcursor of arginine. Ornithine is degraded via glutamic semialdehyde, using the same pathway as proline and glutamic acid. It is also a precursor to IGF the human growth hormone.