期刊
TOXICOLOGY
卷 177, 期 1, 页码 1-9出版社
ELSEVIER SCI IRELAND LTD
DOI: 10.1016/S0300-483X(02)00191-9
关键词
nitric oxide; vasodilation; tyrosyl radical-chemistry
The quenching of the Y-D tyrosyl radical in photosystem II by nitric oxide was reported to result from the formation of a weak tyrosyl radical-nitric oxide complex. This radical/radical reaction is expected to generate an electron spin resonance (ESR)-silent nitrosocyclohexadietione species that can reversibly regenerate the tyrosyl radical and nitric oxide or undergo rearrangement to form 3-nitrosotyrosine. It has been proposed that 3-nitrosotyrosine can be oxidized by one electron to form the tyrosine iminoxyl radical ( > C = N-O-.). This proposal was put forth as a result of ESR detection of the iminoxyl radical intermediate when photosystem II was exposed to nitric oxide. Although the detection of the iminoxyl radical in photosystem II strongly suggested a mechanism involving 3-nitrosotyrosine, the iminoxyl radical ESR spectrum was not unequivocally identified as originating from tyrosine. Subsequently, non-protein L-tyrosine iminoxyl radical was generated by two methods: (1) peroxidase oxidation of synthetic 3-nitroso-N-acetyl-L-tyrosine; and (2) peroxidase oxidation of free L-tyrosine in the presence of nitric oxide. The determination of protein nitrotyrosine content has become a frequently used technique for the detection of nitrosative tissue damage. Protein nitration has been suggested to be a final product of the production of highly reactive nitrogen oxide intermediates (e.g. peroxynitrite) formed in reactions between nitric oxide (NO.) and oxygen-derived species such as superoxide. The enzyme prostaglandin H synthase-2 also forms a tyrosyl radical during its enzymatic catalysis of prostaglandin formation. In the presence of the NO.-generator diethylamine nonoate, the tyrosyl radical of prostaglandin H synthase-2 also changes to that of an iminoxyl radical. Western blot analysis of prostaglandin H synthase-2 after exposure to the NO.-generator revealed nitrotyrosine formation. The results provide a mechanism for nitric oxide-dependent tyrosine nitration that does not require formation of more highly reactive nitrogen oxide intermediates such as peroxynitrite or nitrogen dioxide. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据