Ornithine Aminotransferase Human

Ornithine aminotransferase (OAT) is an enzyme encoded by the OAT gene located on chromosome 10 in humans . This enzyme plays a crucial role in the metabolism of amino acids, specifically in the conversion of ornithine to proline and vice versa . The recombinant form of this enzyme is produced using genetic engineering techniques, allowing for its expression in host organisms such as Escherichia coli .

The OAT enzyme is a pyridoxal-5’-phosphate (PLP)-dependent enzyme that catalyzes the transfer of the delta-amino group from L-ornithine to 2-oxoglutarate, producing L-glutamate-gamma-semialdehyde and L-glutamate . The enzyme functions as a dimer, with each monomer consisting of a large domain, a C-terminal small domain, and an N-terminal region . The large domain contributes most to the subunit interface, while the C-terminal small domain is distant from the two-fold axis .

The OAT protein is primarily expressed in the liver and kidney, but it is also found in the brain and retina . Within cells, the enzyme is localized to the mitochondrion, where it performs its metabolic functions .

The recombinant form of OAT is typically produced by cloning the human OAT gene into an expression vector, which is then introduced into a host organism such as Escherichia coli . The host cells are cultured under conditions that induce the expression of the OAT protein. The protein is then purified using various chromatographic techniques to obtain a high-purity product suitable for research and therapeutic applications .

Mutations in the OAT gene can lead to malfunctioning proteins, resulting in conditions such as gyrate atrophy of the choroid and retina . This condition is characterized by the progressive loss of vision due to the degeneration of the choroid and retina. The mechanism underlying this condition is thought to involve the toxicity of glyoxylate, a byproduct of the OAT-catalyzed reaction .