Grant: Discovery Grants Program - Individual

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.