Molecular mechanism of proton pumping by complex I: A single enzyme study

线粒体是我们体内细胞的发电站。复合物I是在该过程中起关键作用的酶复合物。它利用从化学反应中获得的能量将带正电的质子泵过5纳米的薄膜。这个过程与电池充电没有什么不同。复合物I并不总是在最佳条件下起作用，并且已知是自由基氧物种的来源，其被认为在衰老中具有重要作用。此外，复合物I的功能障碍对（人类）健康有重要的影响，我们想知道复合物I是如何将质子泵过细胞膜的。过去已经进行了许多研究，但泵送机制仍然不清楚，尽管已经公式化了假设，但这些都没有得到实验证明。过去的所有研究都着眼于复合物I的大集合，并形成了这些复合物平均如何发挥作用的图片。然而，我们认为，如果我们逐一研究这些配合物，可以更好地理解泵送机制。我们最近开发了新的实验方法，这些方法非常灵敏，可以检测单个复合物的质子泵。在这个建议中，我们想应用这些实验来研究复合物I。这些结果将使我们更好地了解这些复合物如何在我们的线粒体中发挥作用，以及当它们不能最佳工作时会发生什么。我们要解决的问题是基本的，“蓝天”性质的，但从长远来看，我们希望更深入地了解我们体内产生能量的过程将有助于我们应对通常与衰老有关的疾病，包括阿尔茨海默病和癌症。

Mitochondria are the powerhouses of the cells in our body. Complex I is an enzyme complex that plays a crucial role in this process. It uses the energy obtained from chemical reactions to pump positively charged protons across a 5nm thin membrane. This process is not unlike the charging of a battery. Complex I does not always function under optimal conditions and is known to be source of radical oxygen species, which is believed to have important roles in aging. Furthermore, malfunction of complex I has important consequences for (human) health.We like to know how complex I pumps protons across the membrane. Many studies have already been performed in the past, but the pumping mechanism is still unclear and although hypotheses have been formulised, none of these have been experimentally proven. All studies in the past have looked at large ensembles of complex I and form a picture of how these complexes function on average. However, we think that a better understanding of the pumping mechanism can be obtained if we look at these complexes one by one. We have recently developed new experimental methods that are so sensitive they can detect proton pumping by single complexes. In this proposal we want to apply these experiments to study complex I. The results will give us a better understanding on how these complexes function in our mitochondria and what happens when they do not work optimally. The questions we aim to address are of fundamental, 'blue-sky' nature, but on the long term we hope that deeper understanding of the processes that generate energy in our body will help us to tackle diseases often related with aging, including Alzheimer's disease and cancer.