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首页> 外文期刊>Biophysical Chemistry: An International Journal Devoted to the Physical Chemistry of Biological Phenomena >Evidence for a synergistic salt-protein interaction -- complex patterns of activation vs. inhibition of nitrogenase by salt.
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Evidence for a synergistic salt-protein interaction -- complex patterns of activation vs. inhibition of nitrogenase by salt.

机译：盐蛋白相互作用的证据-复杂的激活模式与盐对固氮酶的抑制作用有关。

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The molybdenum nitrogenase enzyme system, comprised of the MoFe protein and the Fe protein, catalyzes the reduction of atmospheric N(2) to NH(3). Interactions between these two proteins and between Fe protein and nucleotides (MgADP and MgATP) are crucial to catalysis. It is well established that salts are inhibitors of nitrogenase catalysis that target these interactions. However, the implications of salt effects are often overlooked. We have reexamined salt effects in light of a comprehensive framework for nitrogenase interactions to offer an in-depth analysis of the sources of salt inhibition and underlying apparent cooperativity. More importantly, we have identified patterns of salt activation of nitrogenase that correspond to at least two mechanisms. One of these mechanisms is that charge screening of MoFe protein-Fe protein interactions in the nitrogenase complex accelerates the rate of nitrogenase complex dissociation, which is the rate-limiting step of catalysis. This kind of salt activation operates under conditions of high catalytic activity and low salt concentrations that may resemble those found in vivo. While simple kinetic arguments are strong evidence for this kind of salt activation, further confirmation was sought by demonstrating that tight complexes that have previously displayed little or no activity due to the inability of Fe protein to dissociate from the complex are activated by the presence of salt. This occurs for the combination Azotobacter vinelandii MoFe protein with: (a) the L127Delta Fe protein; and (b) Clostridium pasteurianum Fe protein. The curvature of activation vs. salt implies a synergistic salt-protein interaction.
机译：由MoFe蛋白和Fe蛋白组成的钼固氮酶系统催化将大气中N（2）还原为NH（3）。这两种蛋白质之间以及铁蛋白与核苷酸（MgADP和MgATP）之间的相互作用对于催化至关重要。众所周知，盐是靶向这些相互作用的固氮酶催化的抑制剂。但是，盐影响的含义经常被忽略。我们已经根据固氮酶相互作用的全面框架重新检查了盐的作用，以提供对盐抑制源和潜在的表观协同性的深入分析。更重要的是，我们已经确定了与至少两个机制相对应的固氮酶盐活化模式。这些机制之一是在固氮酶复合物中进行MoFe蛋白-Fe蛋白相互作用的电荷筛选可加快固氮酶复合物的解离速率，这是催化的限速步骤。这种盐活化在高催化活性和低盐浓度（类似于体内发现的盐）的条件下进行。尽管简单的动力学论据是这种盐活化的有力证据，但通过证明盐的存在可以激活先前由于铁蛋白无法从复合物中解离而显示出很少或没有活性的紧密复合物，从而寻求进一步的证实。 。对于藤蔓固氮菌MoFe蛋白与：（a）L127Delta Fe蛋白的组合，会发生这种情况。 （b）巴氏梭菌铁蛋白。活化与盐的曲率暗示盐-蛋白质相互作用。

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