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首页> 外文学位 >Conformational dynamics in the electron transfer photocycle of mixed-metal hemoglobin hybrids.
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Conformational dynamics in the electron transfer photocycle of mixed-metal hemoglobin hybrids.

机译：混合金属血红蛋白杂化体电子转移光循环的构象动力学。

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摘要

Proteins are inherently dynamic molecules with movements on many time scales. This thesis focuses on the consequences of those dynamics for long range protein-protein electron transfer (ET), specifically of that which occurs in a flash-initiated photocycle. The studies presented here use mixed-metal hemoglobin (Hb) hybrids substituted with Zn in one of the chain types as an ideal system with which to study ET between protein redox partners docked in a crystallographically defined conformation. Even in this well-defined structure, the "forward" and "back" halves of a flash-induced ET photocycle show influences from dynamics. We show that because each half involves different initial configurational ensembles, it will respond differently when conformational dynamics are modulated through changes in viscosity (eta). The forward ET reaction is initiated in an equilibrium ensemble of mostly non-reactive configurations. The reaction is activated by conformational fluctuations into reactive configuration(s) and thus is impeded when those fluctuations are damped by increasing viscosity. In contrast, the ET intermediate is the product of the photoinitiated forward ET process, and by necessity is generated in one of the non-equilibrium ensemble of ET-optimized configurations. Thus, it returns to the ground state with the fastest rate constant possible unless conformational interconversion first 'breaks the connection' and the complex converts to a non-reactive substate.;To understand how ET and conformational rate constants evolve with eta we have introduced a new comprehensive kinetic-dynamic (KD) model for ET. The KD model incorporates the presence of multiple interconverting substates and characterizes the observed ET kinetics with equations that explicitly include interconversion rates that are well-defined functions of eta. The model is used to describe the ET photocycle of the [alpha1(ZnP),beta 2(Fe+3P(L))]2 (P = protoporphyrin IX, L = N3-, CN-, F-) hybrids from 0-20°C and pHs 6.0-8.0. The results indicate that both the nature of the exogenous ligand and pH have a significant influence on the nature of ET and conformational dynamics observed in the system.
机译：蛋白质是固有的动态分子，具有许多时间尺度的运动。本论文着眼于那些动力学对远距离蛋白质-蛋白质电子转移（ET）的后果，特别是在闪光引发的光循环中发生的后果。本文介绍的研究使用一种在链类型之一中被Zn取代的混合金属血红蛋白（Hb）杂合体作为理想系统，用于研究以晶体学定义的构象停靠的蛋白质氧化还原伙伴之间的ET。即使在这种定义明确的结构中，闪光灯诱导的ET光周期的“正向”和“反向”也显示出动力学的影响。我们表明，由于每一半都涉及不同的初始构象整体，因此当通过粘度（eta）的变化调节构象动力学时，其响应会有所不同。正向ET反应在大多数非反应性构型的平衡系中引发。反应通过构象波动转化为反应性构型而激活，因此当通过增加粘度来抑制那些波动时，反应会受到阻碍。相反，ET中间体是光引发的正向ET过程的产物，因此有必要在ET优化配置的非平衡集合之一中生成该中间产物。因此，除非构象互转换首先“断开连接”且复合物转变为非反应性子态，否则它会以最快的速率常数返回基态。为了了解ET和构象速率常数如何随eta演化，我们引入了ET的新的综合动力学（KD）模型。 KD模型结合了多个相互转换子状态的存在，并通过方程式明确描述了观测到的ET动力学，这些方程式明确包含了eta的明确定义的相互转换率。该模型用于描述[alpha1（ZnP），beta 2（Fe + 3P（L））] 2（P =原卟啉IX，L = N3-，CN-，F-）杂种的ET光循环20°C和pH 6.0-8.0。结果表明，外源配体的性质和pH值都对ET的性质和在系统中观察到的构象动力学有重大影响。

著录项

  • 作者

    Patel, Ami Dasharath.;

  • 作者单位

    Northwestern University.;

  • 授予单位 Northwestern University.;
  • 学科 Chemistry Biochemistry.;Chemistry Physical.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 138 p.
  • 总页数 138
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

  • 入库时间 2022-08-17 11:38:26

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