Studies on the Nitration of Tyrosine, Phenylalanine and Bovine Serum Albumin by Peroxynitrite and Peroxyacetyl Nitrate

• Main Authors: Yu-Wan Chang, 張裕旺
• Other Authors: Jen-Kun Lin
• Format: Others
• Language: en_US
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/49374428562497814264

碩士 === 國立臺灣大學 === 生化學研究所 === 89 === Peroxyacetyl nitrate (PAN, CH3C(O)OONO2) is one of common air pollutants formed by the action of sunlight on volatile organic compounds and nitrogen oxides. PAN may be toxic for at least three reasons: its oxidizing property as a peroxide, its acetylating property as an anhydride, and the toxicity of nitrite formed by breakdown of the compound in solution. PAN, like peroxynitrite (ONOO-), can react with sulfhydryl group and result in enzyme inactivaton. Peroxynitrite, the reaction products of superoxide (O2-) and nitric oxide (．NO), can nitrate and hydroxylate aromatic amino acid acid and guanine base. In our lab previously study, PAN has been shown to react with tyrosine, phenylalanine, trytophane and guanine and these reaction products were similar as peroxynitrite reacting with these compuonds. This suggests that PAN may become peroxynitrite. To test this hypothesis, we compared the nitration reaction characters of peroxynitrite and PAN in present study. We first confirmed that both PAN and peroxynitrite can react with L-tyrosine and result in formation of 3-nitrotyrosine and dityrosine. We also used anti-nitrotyrosine antibody to detect the 3-nitrotyrosine in peroxynitrite- or PAN-treated bovine serum albumin (BSA). The tyrosine nitraton ability of PAN is about 25% of peroxynitrite. Formation of tyrosyl radical was demonstrated. The reaction characteristics including tyrosine nitration inhibited by different free radical scavengers, pH dependency of tyrosine nitration, catalytic effects of bicarbonate and ferric-EDTA, DNA single strand breakage activity and tyrosine nitration inhibited by different tea polyphenols between PAN and peroxynitrite were compared. According to these results, we suggest that PAN would not transform to peroxynitrite. The possible reactive intermediate of PAN will be discussed.