• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Chemistry: A European journal >Metmyoglobin-Catalyzed Exogenous and Endogenous Tyrosine Nitration by Nitrite and Hydrogen Peroxide
【24h】

Metmyoglobin-Catalyzed Exogenous and Endogenous Tyrosine Nitration by Nitrite and Hydrogen Peroxide

机译：亚硝酸盐和过氧化氢对肌红蛋白催化的外源和内源酪氨酸硝化

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Metmyoglobin catalyzes the nitration of various phenolic compounds in the presence of nitrite and hydrogen peroxide.The reaction rate depends on the reactant concentrations and shows saturation behavior.Two competing paths are responsible for the reaction.In the first,myoglobin reacts according to a peroxidase-like cycle forming two active intermediates,which can induce one-electron oxidation of the substrates.The MbFe~(IV)=O intermediate oxidizes nitrite to nitrogen dioxide,which,after reaction with the phenol or with a phenoxy radical,yields the nitrophenol.In the second mechanism,hydrogen peroxide reacts with iron-bound nitrite to produce an active nitrating species,which we assume to be a protein-bound peroxy-nitrite species,MbFe~(III)-N(O)OO.The high nitrating power of the active species is shown by the fact that the catalytic rate constant is essentially independent of the redox properties of the phenol.The occurrence of one or other of these mechanisms depends on the nitrite concentration:at low [NO_2~-] the nitrating agent is nitrogen dioxide,whereas at high [NO_2~-] the peroxyni-trite path is dominant.The myoglobin derivative that accumulates during turnover depends on the mechanism.When the path involving NO_2~centre dot is dominant,the spectrum of the MbFe~(IV)=O intermediate is observed.At high nitrite concentration,the Soret band appears at 416 nm,which we attribute to an iron-peroxynitrite species.The metMb/NO_2~-/H_2O_2 system competitively nitrates the heme and the endogenous tyrosine at position 146 of the protein.Phenolic substrates protect Tyrl46 from nitration by scavenging the active nitrating species.The exposed Tyrl03 residue is not nitrated under the same conditions.
机译：肌红蛋白在亚硝酸盐和过氧化氢的存在下催化各种酚类化合物的硝化反应。反应速率取决于反应物的浓度并表现出饱和行为。两个竞争路径负责该反应。首先，肌红蛋白根据过氧化物酶反应- MbFe〜（IV）= O中间体将亚硝酸盐氧化为二氧化氮，然后与苯酚或苯氧基自由基反应生成硝基苯酚，类似于形成两个活性中间体的循环，可以诱导底物的单电子氧化。在第二种机理中，过氧化氢与结合亚铁的亚硝酸盐反应生成活性的硝化物种，我们认为这是一种蛋白质结合的过氧亚硝酸盐物种，MbFe〜（III）-N（O）OO。催化速率常数基本上与苯酚的氧化还原特性无关，表明了这些活性物种的存在。这些机理中的一种或另一种的发生取决于亚硝酸盐的浓度。浓度：在低[NO_2〜-]时硝化剂是二氧化氮，而在高[NO_2〜-]时过氧亚硝酸盐路径占主导地位。周转期间积累的肌红蛋白衍生物取决于机理。当路径涉及NO_2〜时中心点占主导，观察到MbFe〜（IV）= O中间体的光谱。在高亚硝酸盐浓度下，Soret谱带出现在416 nm处，这归因于铁-过亚硝酸盐物种。metMb / NO_2〜-/ H_2O_2系统竞争性地使蛋白质的146位上的血红素和内源性酪氨酸硝酸化。酚类底物通过清除活性硝化物种来保护Tyrl46免受硝化作用。暴露的Tyrl03残留物在相同条件下不会被硝化。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号