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首页> 美国卫生研究院文献>The Journal of Biological Chemistry >A Twin-track Approach Has Optimized Proton and Hydride Transfer by Dynamically Coupled Tunneling during the Evolution of Protochlorophyllide Oxidoreductase
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A Twin-track Approach Has Optimized Proton and Hydride Transfer by Dynamically Coupled Tunneling during the Evolution of Protochlorophyllide Oxidoreductase

机译：双轨方法通过原氯叶酸内酯氧化还原酶的动态耦合隧道优化了质子和氢化物的转移。

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Protein dynamics are crucial for realizing the catalytic power of enzymes, but how enzymes have evolved to achieve catalysis is unknown. The light-activated enzyme protochlorophyllide oxidoreductase (POR) catalyzes sequential hydride and proton transfers in the photoexcited and ground states, respectively, and is an excellent system for relating the effects of motions to catalysis. Here, we have used the temperature dependence of isotope effects and solvent viscosity measurements to analyze the dynamics coupled to the hydride and proton transfer steps in three cyanobacterial PORs and a related plant enzyme. We have related the dynamic profiles of each enzyme to their evolutionary origin. Motions coupled to light-driven hydride transfer are conserved across all POR enzymes, but those linked to thermally activated proton transfer are variable. Cyanobacterial PORs require complex and solvent-coupled dynamic networks to optimize the proton donor-acceptor distance, but evolutionary pressures appear to have minimized such networks in plant PORs. POR from Gloeobacter violaceus has features of both the cyanobacterial and plant enzymes, suggesting that the dynamic properties have been optimized during the evolution of POR. We infer that the differing trajectories in optimizing a catalytic structure are related to the stringency of the chemistry catalyzed and define a functional adaptation in which active site chemistry is protected from the dynamic effects of distal mutations that might otherwise impact negatively on enzyme catalysis.
机译：蛋白质动力学对于实现酶的催化能力至关重要，但是尚不清楚酶如何进化以实现催化作用。光活化酶原绿叶素氧化还原酶（POR）分别催化在光激发态和基态下连续的氢化物和质子转移，是将运动影响与催化作用联系在一起的出色系统。在这里，我们已经使用了同位素效应和溶剂粘度测量值的温度依赖性来分析与三个蓝细菌POR和相关植物酶中的氢化物和质子转移步骤相关的动力学。我们已经将每种酶的动态图谱与其进化起源相关联。在所有POR酶中都保留了与光驱动的氢化物转移相关的运动，但与热活化质子转移相关的运动是可变的。蓝藻POR需要复杂且溶剂耦合的动态网络以优化质子供体-受体的距离，但进化压力似乎已将植物POR中的此类网络最小化。紫色细菌Goloeobacter violaceus的POR具有蓝细菌和植物酶的特征，这表明在POR的进化过程中其动力学特性已得到优化。我们推断优化催化结构的不同轨迹与所催化化学的严格性有关，并定义了一种功能适应性，其中保护了活性位点化学免受远端突变的动态影响，否则这些突变可能会对酶催化产生负面影响。

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