...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Biochemistry >Effect of binding of Cd~(2+) on bacterial reaction center mutants: proton-transfer uses interdependent pathways
【24h】

Effect of binding of Cd~(2+) on bacterial reaction center mutants: proton-transfer uses interdependent pathways

机译：Cd〜（2+）结合对细菌反应中心突变体的影响：质子转移使用相互依赖的途径

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

In bacterial reaction center of Rhodobacter sphaeroides, Cd~(2+) binds in stoichiometric amount to the protein. In the wild type, this results into a notable decrease of the rates of electron-transfer between the two quinone acceptors after the first (kappa_(AB)(1)) and second flash (kappa_(AB)(2)). We have studied these effects in two single mutants, L209PY and L209PF. L209Pro is situated in a protein region rich in hydrogenbond networkds involving water molecules. We show that (1) the combined effects of Cd~(2+) binding and point mutations have a cumulative consequence in the two mutants, decreasing very substantially the observed rates of electron-transfer. Interestingly, the [Cd~(2+)] titration curves of kappa_(AB)(2) in the L209PY and L209PF mutants are nearly superimosable to those previously reported for the M17DN and L210DN mutants (Paddock, M.L., Feher, G., and Okamura, M.Y.(2000) Proc. Natl. Acad. Sci U.S.A. 97, 1548-1553). These observations suggest a common effect of all of these mutations (L209, M17, L210) on the protonation state of the histidine cluster to which Cd~(2+) binds; (2) in the L209PY mutant, the pH titration curves of kappa_(AB)(1), kappa_(AB)(2), and kappa_H~+, the proton-transfer rate at the second flash, are systematically downshifted by 1.5-2 pH units in the presence of 300 muM Cd~(2+), similarly to the wid type RCs (Gerencser, L, and Maroti, P. (2001) Biochemistry 40, 1850-1860). We propose that Cd~(2+) binding influences the electrostatics of interdependent ways of proton penetration within the protein, involving at least, directly or indirectly, L209P, L210D, and M17D, probably in conjunction with hydrogen-bonded connected water molecules.
机译：在球形球形红细菌的细菌反应中心，Cd〜（2+）以化学计量的量与蛋白质结合。在野生型中，这导致第一次（kappa_（AB）（1））和第二次闪光（kappa_（AB）（2））之后两个醌受体之间的电子转移速率显着降低。我们已经在两个单一突变体L209PY和L209PF中研究了这些作用。 L209Pro位于一个富含涉及水分子的氢键网络的蛋白质区域。我们表明（1）Cd〜（2+）结合和点突变的组合效应在两个突变体中都有累积的结果，从而大大降低了观察到的电子传递速率。有趣的是，L209PY和L209PF突变体中kappa_（AB）（2）的[Cd〜（2+）]滴定曲线几乎与先前报道的M17DN和L210DN突变体（Paddock，ML，Feher，G。和Okamura，MY（2000）美国国家科学院院刊97，1548-1553）。这些观察结果表明所有这些突变（L209，M17，L210）对与Cd〜（2+）结合的组氨酸簇的质子化状态具有共同的影响。 （2）在L209PY突变体中，kappa_（AB）（1），kappa_（AB）（2）和kappa_H〜+（第二次闪蒸时的质子转移速率）的pH滴定曲线被系统地下移了1.5-在300μMCd〜（2+）存在下的2个pH单位，类似于wid型RC（Gerencser，L和Maroti，P.（2001）Biochemistry 40，1850-1860）。我们建议Cd〜（2+）结合影响质子渗透蛋白质中相互依赖的方式的静电，至少直接或间接地涉及L209P，L210D和M17D，可能与氢键连接的水分子结合。

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