CAUSE & EFFECT OF DIMER ASYMMETRY IN MERCURIC REDUCTASE

汞离子还原酶催化双电子还原 汞(II)作为细菌中的关键步骤 汞(II)和有机汞的解毒。这种酶是一种 每二聚体具有两个界面活性中心的同源二聚体蛋白，其 广泛的证据表明，感觉到氧化还原和/或配体状态 彼此之间。我们最近发现，在氧化剂中 酶与体积较大的硫醇配位汞(II)的半反应 化合物，可与体内底物、亚基间比较 在催化循环中，相互作用似乎是关键的，而 较简单的汞(II)化合物可以绕过正常的进入路线，并且 相应的亚基间相互作用。我们使用MidasPlus来识别 建议的小与大汞(II)底物的进入途径 目前正在使用该软件帮助识别 这些途径上的其他残基可能参与 配体交换过程和代表突变的靶点 分析。我们还使用该软件来帮助可视化 蛋白质的静电势，尤指作为配体或 氧化还原状态随着这可能是一个关键因素的假设而改变 在子单元间的通信中。我们计划的一个新方向 EQUEST是对酶的金属离子特异性的再工程。 根据我们最近确定的绑定路径，我们将使用 考虑我们可能是什么类型的金属离子络合物的图表 能够适应需要做出的改变以完成任务。

Mercuric ion reductase catalyzes the two-electron reduction of Hg(II) to elemental mercury as the key step in bacterial detoxification of Hg(II) and organomercuricals. The enzyme is a homodimeric protein with two interfacial active sites per dimer, which extensive evidence indicates sense the redox and/or ligand state of each other. We have recently found that in the oxidative half-reaction of the enzyme with bulky thiol-liganded Hg(II) compounds, comparable to the in vivo substrate, intersubunit interactions appear to be critical in the catalytic cycle while simpler Hg(II) compounds can bypass the normal entry route and the corresponding intersubunit interactions. We use MidasPlus to identify proposed entry pathways for the small verses large Hg(II) substrates and are currently using the software to aid in the identification of additional residues along these pathways that may participate in the ligand exchange processes and represent targets for mutational analysis. We are also using the software to help visualize the electrostatic potential of the protein, especially as the liganded or redox state changes with the hypothesis that this may be a key element in the intersubunit communication. A new direction that we plan to pursue is a reengineering of the metal ion specificity of the enzyme. With our recent identification of pathways for binding, we will use the graphics to consider what types of metal ion complexes we might be able to accomodate and what changes to make to accomplish the task.