CAUSE & EFFECT OF DIMER ASYMMETRY IN MERCURIC REDUCTASE

汞还原酶是具有两个界面的同源二聚体蛋白质， 活性位点/二聚体。 大量的证据，用酶从 假单胞菌转座子Tn 501，表明活性位点 环境是不对称的， 在两个位点结合，但在没有配体的情况下对称。 以来 复合酶是催化相关的，我们提出了一个作用， 催化机制的不对称性。 为了阐明 角色，我们检查了一些配体，以确定哪些部分的 配体可能参与诱导不对称性。 另外我们 评价了该酶与多种 Hg（II）化合物，这表明亚基间的相互作用 可能主要是由于Hg（II）底物的性质，因为它是 在体内呈现给酶。 使用简单的Hg（II）盐， 可以取消子单元间通信。 与新 信息，我们正在使用MidasPlus来确定特定的途径， 活动站点之间的通信，并评估 不同的Hg（II）化合物进入活性部位的途径。 的 计算机图形学实验室为我们提供了宝贵的资源， 努力理解复杂。

Mercuric reductase is a homodimeric protein with two interfacial active sites per dimer. Extensive evidence, obtained with enzyme from a Pseudomonas transposon Tn501, indicates that the active site environments are asymmetric when pyridine nucleotide substrates are bound at both sites, but symmetric in the absence of ligands. Since the complexed enzyme is catalytically relevant, we proposed a role for the asymmetry in the cataytic mechanism. To elucidate the mechanistic role, we examined a number of ligands to determine which portions of ligands may be involved in induction of asymmetry. In addition, we evaluated the oxidative half- reaction of the enzyme with a variety of Hg(II) compounds, which indicates that the intersubunit interaction may primarily result from the nature of the Hg(II) substrate as it is presented to the enzyme in vivo. With simpler Hg(II) salts, the need for intersubunit communication may be abolished. With the new information, we are using MidasPlus to identify specific pathways for communication between the active sites and to evaluate points of access for the different Hg(II) compounds to the active site. The Computer Graphics Laboratory provides a valuable resource for our efforts to understand the complex.