• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Chemistry: A European journal >Oxidation of Zn(Cys)_4 zinc finger peptides by O_2 and H_2O_2: Products, mechanism and kinetics
【24h】

Oxidation of Zn(Cys)_4 zinc finger peptides by O_2 and H_2O_2: Products, mechanism and kinetics

机译：O_2和H_2O_2氧化Zn（Cys）_4锌指肽的产物，机理和动力学

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

The reactivity of a series of Zn(Cys)_4 zinc finger model peptides towards H_2O_2 and O_2 has been investigated. The oxidation products were identified by HPLC and ESI-MS analysis. At pH<7.5, the zinc complexes and the free peptides are oxidised to bis-disulfide-containing peptides. Above pH 7.5, the oxidation of the zinc complexes by H_2O_2 also yields sulfinate- and sulfonate-containing overoxidised peptides. At pH 7.0, monitoring of the reactions between the zinc complexes and H_2O_2 by HPLC revealed the sequential formation of two disulfides. Several techniques for the determination of the rate constant for the first oxidation step corresponding to the attack of H_2O_2 by the Zn(Cys)_4 site have been compared. This rate constant can be reliably determined by monitoring the oxidation by HPLC, fluorescence, circular dichroism or absorption spectroscopy in the presence of excess ethyleneglycol bis(2-aminoethyl ether)tetraacetic acid. In contrast, monitoring of the release of zinc with 4-(2-pyridylazo) resorcinol or of the thiol content with 5,5′-dithiobis(2-nitrobenzoate) did not yield reliable values of this rate constant for the case in which the formation of the second disulfide is slower than the formation of the first. The kinetic measurements clearly evidence a protective effect of zinc on the oxidation of the cysteines by both H_2O_2 and O_2, which points to the fact that zinc binding diminishes the nucleophilicity of the thiolates. In addition, the reaction between the zinc finger and H _2O_2 is too slow to consider zinc fingers as potential sensors for H_2O_2 in cells.
机译：研究了一系列Zn（Cys）_4锌指模型肽对H_2O_2和O_2的反应性。氧化产物通过HPLC和ESI-MS分析鉴定。在pH ＜7.5时，锌络合物和游离肽被氧化成含双二硫的肽。在pH 7.5以上，H_2O_2对锌络合物的氧化作用还会产生含亚磺酸盐和磺酸盐的过氧化肽。在pH 7.0下，通过HPLC监测锌配合物与H_2O_2之间的反应可发现依次形成了两个二硫化物。比较了确定第一氧化步骤速率常数的几种技术，该速率常数对应于Zn（Cys）_4位对H_2O_2的攻击。该速率常数可以通过在过量的乙二醇双（2-氨基乙基醚）四乙酸存在下通过HPLC，荧光，圆二色性或吸收光谱监测氧化来可靠地确定。相反，用4-（2-吡啶基偶氮）间苯二酚监测锌的释放或用5,5'-二硫代双（2-硝基苯甲酸酯）监测硫醇含量不能得到可靠的该速率常数值，在这种情况下，第二种二硫化物的形成要比第一种二硫化物的形成慢。动力学测量清楚地证明了锌对H_2O_2和O_2对半胱氨酸的氧化的保护作用，这表明锌结合降低了硫醇盐的亲核性这一事实。此外，锌指和H _2O_2之间的反应太慢，以至于无法将锌指视为细胞中H_2O_2的潜在传感器。

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