Collaborative Research: Understanding Electron Bifurcation in Methanogenic Archaea

通过这一奖项，生命过程化学计划资助奥本大学的Evert Duin博士和华盛顿大学的John Leigh博士研究电子分叉的重要过程，电子分叉发生在生命系统将能量从一种形式转换为另一种形式时。在这个过程中，两个电子以相同的势进入系统，但当它们离开时，一个的势比另一个低得多。因此，电子分叉使生物分子的上坡、高能量、电子还原成为可能，因为下坡氧化伴随发生，这平衡了能量消耗和生成。这个过程已经在古生代的甲烷生产和消费功能中观察到，它生产生物燃料，但也在其他形式的生命中观察到，包括我们自己的身体。了解这一过程是如何运作的，可能有助于提高沼气的生产，或有助于优化甲烷转化为生物柴油，并可以帮助我们回答各种与健康相关的问题。这项研究对所有教育水平的学生成为下一代科学家的准备工作产生了更广泛的影响。这个项目的合作性质涉及来自美国不同地理区域的小组，为学生创造了一个环境，让他们获得跨学科和合作研究的技能。电子分叉使酶能够通过同时产生一个具有高氧化还原潜力的电子来产生具有非常低的氧化还原潜力的电子。这就消除了将先前的电子转移步骤与ATP水解相耦合的需要。分叉过程总是涉及一个苯二酚或黄素基团。Duin和Leigh小组将研究氢酶：异二硫化物还原酶复合体的电子分叉，该复合体在铁-硫簇中包含铁离子。理论认为，一些铁-硫团簇在电子分叉过程中发挥了重要作用，它们向中心黄素提供电子，然后接受高势或低势电子。定点突变将被用来改变铁-硫簇和黄素及其直接环境。这些变化对团簇和黄素的电子和磁性的影响将通过吸收光谱、电子顺磁共振和磁圆二色谱来评估，而对分叉过程的影响将通过测定团簇和黄素的氧化还原性质和氧化还原过程的动力学来考察。

With this award, the Chemistry of Life Processes Program is funding Dr. Evert Duin of Auburn University and Dr. John Leigh of the University of Washington to study the important process of electron bifurcation, which occurs when living systems convert energy from one form to another. In this process, two electrons enter the system with identical potential, but when they exit, one has a much lower potential than the other. Consequently, electron bifurcation makes possible an uphill, energy-demanding, electron reduction of a biological molecule because a downhill oxidation occurs concomitantly, which balances the energy consumption and generation. The process has been observed in the methane-producing and -consuming functions of Archaea, which produce biofuels, but also in other forms of life, including our own bodies. Understanding how this process works could be beneficial for improving the production of biogas or helping to optimize the conversion of methane to biodiesel and could help us answer a variety of health-related questions. The research has a further broader impact on the preparation of students at all educational levels to become the next generation of scientists. The collaborative nature of the project that involves groups from different geographic regions of the United States creates an environment in which the students acquire skills for interdisciplinary and collaborative research.Electron bifurcation enables enzymes to create electrons with a very low redox potential by simultaneously creating an electron with a high redox potential. This eliminates the need to couple the former electron transfer step to ATP hydrolysis. The bifurcation process always involves a quinone or flavin group. The Duin and Leigh groups will study the electron bifurcation by the hydrogenase:heterodisulfide reductase complex, which contains iron ions within iron-sulfur clusters. The theory is that some of the iron-sulfur clusters play an important part in the electron bifurcation process by donating electrons to the central flavin and then accepting either the high or low potential electrons. Site-direct mutagenesis will be used to make changes to the iron-sulfur clusters and to the flavins and their direct envoironment. The consequences of these changes on the electronic and magnetic properties of the clusters and flavin will be evaluated by absorption, electron paramagnetic resonance, and magnetic circular dichroism spectroscopies and on the bifurcation process will be examined by determining the redox properties of the clusters and flavin and the kinetics of the redox processes.