...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Biochemistry >The Relationship of the Redox Potentials of Thioredoxin and Thioredoxin Reductase from Drosophila melanogaster to the Enzymatic Mechanism: Reduced Thioredoxin Is the Reductant of Glutathione in Drosophila
【24h】

The Relationship of the Redox Potentials of Thioredoxin and Thioredoxin Reductase from Drosophila melanogaster to the Enzymatic Mechanism: Reduced Thioredoxin Is the Reductant of Glutathione in Drosophila

机译：果蝇中硫氧还蛋白和硫氧还蛋白还原酶的氧化还原电位与酶机制的关系：硫氧还蛋白还原是果蝇中谷胱甘肽的还原剂。

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

Thioredoxin reductase from Drosophila melanogaster (DmTrxR) catalyzes the reversible transfer of reducing equivalents between NADPH and thioredoxin (Trx), a small protein that is involved in a wide variety of biological redox processes. The catalysis involves three essential redox states of the enzyme: the oxidized form of DmTrxR (E_(ox)), the 2-electron-reduced forms (EH_2), and the 4-electron-reduced forms (EH4). In the present work, the macroscopic redox potentials of E_(0X)/EH_2 and EH_2/EH_4 couples were determined to be -272 ± 5 mV for E_m(E_(0X)/EH_2) and -298 ± 11 mV for E_m(EH_2/EH_4O on the basis of redox equilibria between DmTrxR and NADH. The value for E_m(EH_2/EH_4) obtained from the steady-state kinetics of the TrxR-catalyzed reaction between NADPH and D. melanogaster Trx-2 (DmTrx-2) was reasonably consistent with that based on redox equilibria. The redox potential of the Trx-(S)2/Trx-(SH)2 couple from D. melanogaster Trx-2 (DmTrx-2) was calculated to be -275.4 ± 0.3 mV by using the Nernst equation and the K_(eq) for the equilibrium of the reaction involving NADP/NADPH and Trx-(S)_2/Trx-(SH)_2. For the accurate determination of the K_(eq), an improved protocol has been developed to minimize errors that can be introduced by using starting concentrations far from equilibrium of the TrxR-catalyzed reaction between NADPH and Trx. This improved approach gives an E_m of -284.2 ± 1.0 mV for Escherichia coli Trx and -271.9 ± 0.4 mV for Plasmodium falciparum Trx, which agree well with published values (-283 or -285 mV and -270 mV, respectively). The redox potentials determined herein provide further direct evidence for the proposed catalytic mechanism of DmTrxR, and cast new light on the essential role of the DmTrx system in cycling GSSG/GSH and maintaining the intracellular redox homeostasis in D. melanogaster where glutathione reductase is absent.
机译：果蝇的硫氧还蛋白还原酶（DmTrxR）催化NADPH和硫氧还蛋白（Trx）之间的还原等效物的可逆转移，硫氧还蛋白（Trx）是一种参与多种生物氧化还原过程的小蛋白质。催化涉及酶的三个基本氧化还原状态：DmTrxR的氧化形式（E_（ox）），2-电子还原形式（EH_2）和4-电子还原形式（EH4）。在目前的工作中，确定E_（0X）/ EH_2和EH_2 / EH_4对的宏观氧化还原电势对于E_m（E_（0X）/ EH_2）为-272±5 mV，对于E_m（EH_2）为-298±11 mV / EH_4O是基于DmTrxR和NADH之间的氧化还原平衡得出的，E_m（EH_2 / EH_4）的值由TrxR催化的NADPH和D. melanogaster Trx-2（DmTrx-2）之间的稳态动力学得出。与基于氧化还原平衡的氧化还原电位合理地一致，通过计算，黑腹果蝇Trx-2（DmTrx-2）的Trx-（S）2 / Trx-（SH）2对的氧化还原电势为-275.4±0.3 mV使用能斯特方程和K_（eq）来平衡涉及NADP / NADPH和Trx-（S）_2 / Trx-（SH）_2的反应。为了精确确定K_（eq），改进了协议已开发出最小化使用起始浓度而不是TrxR催化的NADPH和Trx之间的平衡反应引入的误差的改进方法，其E_m为-284.2±1.0 mV fo r恶性疟原虫Trx的大肠杆菌Trx和-271.9±0.4 mV，与已公布的值非常吻合（分别为-283或-285 mV和-270 mV）。本文确定的氧化还原电势为拟议的DmTrxR催化机理提供了进一步的直接证据，并为DmTrx系统在循环GSSG / GSH和维持黑腹果蝇中缺乏谷胱甘肽还原酶的细胞内氧化还原稳态方面的重要作用提供了新的思路。

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