Arginase

• OMIM: 608 313
• UniProt: P05089

Arginase 1 (also: liver arginase, ARG1 ) is the enzyme that catalyzes the last reaction step in the urea cycle of vertebrates. The arginases is a group of isozymes that occur in all living beings and bring about the degradation of the amino acid arginine to ornithine and urea. In humans, mutations in the ARG1 gene to Arginase deficiency, and this lead to a urea cycle defect with hyperammonemia. Variants of arginase in asthma patients were associated with side effects on beta - 2-agonists. Another variant showed an association with the risk of myocardial infarction.

Neutrophils modulate the immune response by secreting arginase. In psoriasis lesions arginase is overexpressed. This leads to reduced availability of nitric oxide in tissue because Arginase competes with NO synthase for arginine. The same competition within macrophages is exploited by intracellular pathogens such as Mycobacterium tuberculosis, Toxoplasma gondii and another to evade the immune response.

The cAMP-dependent regulation of ARG1 expression is modulated by protein kinase Al and is dependent on histone deacetylation.

Catalyzed reaction

H2O ⇔

Arginine is hydrolyzed to ornithine and urea.