title: Damage of amino acids and proteins induced by nitrogen dioxide, a free radical toxin, in air.
abstract: Damage of amino acids and proteins induced by nitrogen dioxide, a free radical toxin in polluted air, was investigated. When nitrogen dioxide (30-90 ppm) in air was exposed to a solution of an amino acid at pH 7.5 for several hours, tryptophan and tyrosine were damaged. Degradation of tryptophan was accompanied by formation of a nitroindole derivative. Decrease of tyrosine was accompanied by formation of 3-nitrotyrosine and fluorescent dityrosine. When nitrogen dioxide was exposed to a solution of bovine serum albumin, human gamma-globulin and bovine eye lens alpha-crystallin, the proteins were crosslinked by nondisulfide bonds. Tryptophan and tyrosine residues in the proteins were extensively decreased, and significant amounts of 3-nitrotyrosine and fluorescent dityrosine were formed. The modification of the proteins with nitrogen dioxide in air may have toxicological significance. Because fluorescent dityrosine is detected in a wide variety of natural proteins, nitrogen dioxide may play a role in its occurrence in natural proteins.
authors.affiliation: Tokyo College of Pharmacy, Hachioji, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Kikugawa
authors.forename: T
authors.initials: T
authors.lastname: Kato
authors.forename: Y
authors.initials: Y
authors.lastname: Okamoto
mesh_terms: D000393:Air Pollutants / Q000633:toxicity; D000596:Amino Acids / Q000737:chemistry / Q000187:drug effects*; D000818:Animals; D002417:Cattle; D003432:Cross-Linking Reagents; D003459:Crystallins / Q000737:chemistry / Q000187:drug effects; D005609:Free Radicals; D006801:Humans; D066298:In Vitro Techniques; D009585:Nitrogen Dioxide / Q000633:toxicity*; D011506:Proteins / Q000737:chemistry / Q000187:drug effects*; D012710:Serum Albumin, Bovine / Q000737:chemistry / Q000187:drug effects; D014364:Tryptophan / Q000737:chemistry / Q000187:drug effects; D014443:Tyrosine / Q000031:analogs & derivatives / Q000737:chemistry / Q000187:drug effects; D005719:gamma-Globulins / Q000737:chemistry / Q000187:drug effects
chemical_list: D000393:Air Pollutants; D000596:Amino Acids; D003432:Cross-Linking Reagents; D003459:Crystallins; D005609:Free Radicals; D011506:Proteins; D005719:gamma-Globulins; D012710:Serum Albumin, Bovine; D014443:Tyrosine; D014364:Tryptophan; C007543:dityrosine; D009585:Nitrogen Dioxide