The measurement of 3-nitrotyrosine is used to test the oxidative and nitrosative stress of the body.
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Nitrotyrosine is a nitration product of the amino acid tyrosine caused by active nitrogen radicals such as peroxynitrite anion and nitrogen dioxide. Nitrotyrosine is considered an indicator of cell damage, inflammation, and production of NO (nitric oxide). Nitrotyrosine is formed in the presence of NO. In many pathological conditions, oxidative stress increases the production of radicals peroxide (O2-) and NO-forming peroxynitrite (ONOO-), a very active and destructive free radical. Peroxynitrite radical is capable of oxidizing several lipoproteins and nitrifying tyrosine found in many proteins. Because peroxynitrite production is difficult to determine, nitrotyrosine measurement is an excellent measurable indicator for indirect detection of the ONOO- anion. Elevated concentrations of 3-nitrotyrosine are detected in a large number of pathological conditions and are considered an indicator of stress caused by reactive nitrogen radicals (nitrosative stress - in proportion to oxidative stress).
Nitrotyrosine is involved in the pathogenesis of many inflammatory and degenerative diseases of humans such as Alzheimer's disease, atherosclerosis, other cardiovascular diseases, asthma, diabetes mellitus, and other pathological conditions caused by endothelial damage. Oxidative/nitrosative stress has been shown to be a mechanism of secondary neuronal damage in traumatic brain injury. Nitrotyrosine in cerebrospinal fluid can be an important indicator of nitrosative stress in the central nervous system. Nitrotyrosine has also been linked to degenerative lesions of dopaminergic neurons. The amino acid tyrosine is a precursor molecule of dopamine, a very important neurotransmitter for mobility, attention, learning, circadian rhythms, and other biological processes.
Elevated serum 3-nitrotyrosine levels are detected in rheumatoid arthritis and other autoimmune diseases, inflammatory bowel disease, neoplasms, neurodegenerative diseases, Alzheimer's disease, amyotrophic lateral sclerosis, Huntington's disease, CNS injuries, diabetes mellitus and in its complications, in septic shock and in celiac disease. Nitrotyrosine is not normally detected in healthy individuals
3-Nitrotyrosine levels can be reduced by using N-acetylcysteine, which is a precursor of glutathione, a very important endogenous antioxidant molecule in the body.
Free nitrotyrosine is metabolized to form 3-nitro-4-hydroxyphenylacetic acid (NHPA) which is excreted in the urine.
