Function and assembly of cytochrome oxidase

生物体通过一系列酶催化反应从食物中提取能量。在高等生物体中，能量捕获的最大贡献者是线粒体细胞器中发现的一系列酶，被称为呼吸链。呼吸链将电子从还原底物传递给氧。在这种受控燃烧过程中，一些能量被捕获，一些能量以热的形式释放。捕获的能量，最初是通过线粒体膜形成的电和化学梯度，被用来制造5'-三磷酸腺苷（ATP）。ATP是生物学中能量交换的分子，用于促进细胞运动、细胞间通讯和营养摄取等过程。细胞色素氧化酶是生物呼吸链上的一种燃烧氧气的酶，是该应用研究的主要焦点。电子和质子的转移是构成催化过程的基本步骤。我们正在研究细胞色素氧化酶催化的电子和质子转移的物理细节，以及它们如何耦合在一起以节省能量。此外，我们对细胞色素氧化酶组装的过程感兴趣。细菌细胞色素氧化酶是由四个蛋白质亚基和一组五种氧化还原活性金属离子组成的。该复合体的组装涉及许多辅助蛋白。其中一种辅助蛋白（即SCO）被提议将铜传递给细胞色素氧化酶。铜的递送不仅要求SCO表现出选择性的、高亲和力的金属结合，而且SCO必须将结合的铜释放到细胞色素氧化酶组装复合物内的特定位点。因此，我们研究的进一步目标是对SCO的金属结合特性及其与细胞色素氧化酶的相互作用进行详细的物理表征。该计划的一个重要组成部分是培养本科生、技术人员、研究生和博士后的生化技能，包括膜蛋白化学、分子生物学和生物物理方法，并将他们的结果置于细胞功能的背景下。

Living organisms extract energy from food in a series of enzyme-catalyzed reactions. The largest contributor to energy capture in higher organisms is a series of enzymes found in the mitochondrial organelle and referred to as the respiratory chain. The respiratory chain passes electrons from reduced substrates to oxygen. During this controlled burn some energy is captured and some is released as heat. The energy captured, initially as an electrical and chemical gradient formed across the mitochondrial membrane, is spent to make adenosine 5'-triphosphate (ATP). ATP is the molecule of energy exchange in biology and is used to fuel such processes as cell movement, intercellular communication and nutrient uptake.Cytochrome oxidase is an enzyme of the respiratory chain in organisms that burn oxygen and is the major focus of the research in this application. Electron and proton transfer are the fundamental steps that comprise the catalytic process. We are studying physical details of electron and proton transfer catalyzed by cytochrome oxidase, and how they are coupled together to conserve energy. In addition we are interested in the process of cytochrome oxidase assembly. Bacterial cytochrome oxidase is composed of four protein subunits together with a set of five redox-active metal ions. Assembly of this complex involves many accessory proteins. One of these accessory proteins (i.e., SCO) is proposed to deliver copper to cytochrome oxidase. Copper delivery not only requires that SCO exhibit selective, high affinity metal binding, but also SCO must release bound copper to a specific site within the cytochrome oxidase assembly complex. Therefore, a further objective of our research is a detailed physical characterization of the metal binding properties of SCO and its interactions with cytochrome oxidase.An intimate component of this program is the training of undergraduate students, technicians, graduate students and post-doctoral persons in biochemical skills including membrane protein chemistry, molecular biology and biophysical methods, and to place their results in the context of cellular function.