• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文学位 >Studying Heme Electrochemistry in Heme Proteins and Quinone Binding in Purple Bacterial Reaction Center Using Multi-Conformation Continuum Electrostatics.
【24h】

Studying Heme Electrochemistry in Heme Proteins and Quinone Binding in Purple Bacterial Reaction Center Using Multi-Conformation Continuum Electrostatics.

机译：使用多构象连续体静电学研究血红素蛋白中的血红素电化学和紫色细菌反应中心中的醌结合。

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

Hemes are important redox cofactors. They are found in a variety of proteins and show a diversity of functions. The free energy of heme reduction in different proteins is found to vary over more than 18 kcal/mol. It is a challenge to determine how proteins manage to achieve this enormous range of Ems with a single type of redox cofactor. Proteins containing 141 unique hemes of a-, b- and c-type, with bis-His, His-Met and aquo-His ligation were calculated using Multi-Conformation Continuum Electrostatics (MCCE). The experimental Ems range over 800 mV from -350 mV in cytochrome c3 to 450 mV in cytochrome c peroxidase (vs. SHE). The quantitative analysis of the factors that modulate heme electrochemistry includes the interactions of the heme with its ligands, the solvent, the backbone, and sidechains. MCCE calculated Ems are in good agreement with measured values. The overview of heme proteins with known structures and Ems shows the lowest and highest potential hemes are c-type, while the b-type hemes are found in the middle Em range. In solution, bis-His ligation lowers the Em by ≈205 mV relative to hemes with His-Met ligands. The bis-His, aquo-His and His-Met ligated b-type hemes all cluster about Ems which are ≈200 mV more positive in protein than in water. In contrast, the low potential bis-His c-type hemes are shifted little from in solution, while the high potential His-Met c-type hemes are raised by ≈300 mV from solution. The analysis shows that no single type of interaction can be identified as the most important in setting heme electrochemistry in proteins. Therefore, different proteins use different aspects of their structures to modulate the in situ heme electrochemistry.;Quinones play important roles in mitochondrial and photosynthetic energy conversion acting as intramembrane, mobile electron and proton carriers between catalytic sites in various electron transfer proteins. They display different affinity, selectivity, functionality and exchange dynamics in different binding sites. The computational analysis of quinone binding sheds light on the requirements for quinone affinity and specificity. The affinities of ten oxidized, neutral benzoquinones (BQs) were measured for the high affinity QA site in the detergent solubilized Rhodobacter sphaeroides bacterial photosynthetic reaction center. Multi-Conformation Continuum Electrostatics (MCCE) was then used to calculate their relative binding free energies by Grand Canonical Monte Carlo sampling with a rigid protein backbone, flexible ligand and side chain positions and protonation states. Van der Waals and torsion energies, Poisson-Boltzmann continuum electrostatics and accessible surface area dependent ligand-solvent interactions are considered. The affinities are dominated by favorable protein-ligand van der Waals rather than electrostatic interactions. Each quinone appears in a closely clustered set of positions. Methyl and methoxy groups move into the same positions as found for the native quinone.
机译：血红素是重要的氧化还原辅助因子。它们存在于多种蛋白质中，并具有多种功能。发现不同蛋白质中血红素还原的自由能变化超过18 kcal / mol。确定蛋白质如何通过单一类型的氧化还原辅助因子来实现如此广泛的Ems是一个挑战。使用多构象连续体静电学（MCCE）计算含有141个a-，b-和c-型，双-His，His-Met和aquo-His连接的独特血红素的蛋白质。实验性Ems的范围在800 mV以上，从细胞色素c3中的-350 mV到细胞色素c过氧化物酶中的450 mV（相对于SHE）。调节血红素电化学的因素的定量分析包括血红素与其配体，溶剂，主链和侧链的相互作用。 MCCE计算得出的Ems与测量值非常吻合。具有已知结构和Ems的血红素蛋白概述显示，最低和最高的潜在血红素为c型，而b型血红素位于Em的中等范围。在溶液中，相对于具有His-Met配体的血红素，bis-His的连接使Em降低了205 mV。 bis-His，aquo-His和His-Met连接的b型血红素均聚集在Ems周围，而Ems的蛋白质阳性率比水中高200 mV。相反，低电势的双-His c-型血红素从溶液中转移很少，而高电势的His-Met c-型血红素从溶液中升高了约300 mV。分析表明，没有任何一种相互作用类型可以确定是蛋白质中血红素电化学的最重要组成部分。因此，不同的蛋白质利用其结构的不同方面来调节原位血红素电化学。奎因酮在线粒体和光合作用的能量转换中起着重要的作用，充当各种电子转移蛋白质中催化位点之间的膜内，移动电子和质子载体。它们在不同的结合位点显示出不同的亲和力，选择性，功能性和交换动力学。醌结合的计算分析阐明了对醌亲和力和特异性的要求。测量了十种氧化的中性苯醌（BQs）的亲和力，以了解去污剂溶解的球形球形红细菌细菌光合作用反应中心中的高亲和力QA位点。然后，通过具有刚性蛋白质骨架，柔性配体和侧链位置以及质子化状态的Grand Canonical Monte Carlo采样，使用多构象连续静电学（MCCE）来计算其相对结合自由能。考虑了范德华力和扭转能，泊松-玻耳兹曼连续体静电以及与可及表面积有关的配体-溶剂相互作用。亲和力主要由有利的蛋白质-配体范德华力而非静电相互作用决定。每个醌以紧密聚集的一组位置出现。甲基和甲氧基移至与天然醌相同的位置。

著录项

  • 作者

    Zheng, Zhong.;

  • 作者单位

    City University of New York.;

  • 授予单位 City University of New York.;
  • 学科 Chemistry Biochemistry.;Biophysics General.;Chemistry Physical.
  • 学位 Ph.D.
  • 年度 2011
  • 页码 124 p.
  • 总页数 124
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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