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

线粒体是我们体内细胞的动力源。复合体I是一种酶复合体，在这个过程中起着至关重要的作用。它利用从化学反应中获得的能量，将带正电的质子泵过一层5纳米的薄膜。这一过程与给电池充电没有什么不同。络合物I并不总是在最佳条件下发挥作用，它被认为是自由基氧物种的来源，被认为在衰老中具有重要作用。此外，复合体I的故障对(人类)健康有重要影响。我们想知道复合体I如何将质子泵过膜。过去已经进行了许多研究，但泵浦机制仍然不清楚，尽管已经提出了假说，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体I的大型集合，并形成了这些复合体平均如何发挥作用的图景。然而，我们认为，如果我们逐一研究这些络合物，可以对泵浦机理有更好的了解。我们最近开发了新的实验方法，这些方法非常灵敏，可以检测到单个络合物的质子泵浦。在这项提议中，我们想要将这些实验应用于研究复合体I。结果将使我们更好地了解这些复合体在我们的线粒体中是如何发挥作用的，以及当它们不能以最佳方式工作时会发生什么。我们致力于解决的问题是根本性的、蓝天性质的，但从长远来看，我们希望更深入地了解我们身体中产生能量的过程将有助于我们应对经常与衰老有关的疾病，包括阿尔茨海默氏症和癌症。

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.