Ornitintranszamináz

Ornitintranszamináz, also known as ornithine aminotransferase or OAT, is an enzyme that plays a crucial role in amino acid metabolism. Specifically, it catalyzes the reversible transamination reaction between L-ornithine and alpha-ketoglutarate, producing L-glutamate and alpha-ketoglutarate semialdehyde. This enzyme is found in various tissues throughout the body, with particularly high activity in the liver and kidneys.

The primary function of ornithine transaminase is within the urea cycle and the metabolism of proline and arginine. In the urea cycle, it helps convert ornithine, which is produced from arginine breakdown, into glutamate. This is a key step in the detoxification of ammonia, a toxic byproduct of protein metabolism, which is then excreted from the body as urea. Beyond the urea cycle, OAT is also involved in the interconversion of ornithine and glutamate, which are important for the synthesis of proline, a semi-essential amino acid.

Mutations in the gene encoding ornithine transaminase (OAT gene) can lead to a serious genetic disorder called gyrate atrophy of the choroid and retina. This condition is characterized by progressive degeneration of the choroid and retina in the eye, leading to impaired vision and eventual blindness. The deficiency in OAT activity results in the accumulation of ornithine in the blood and tissues, which is believed to be toxic to the retinal pigment epithelium.