This project has two components. The first involves the structural and functional properties of the 1:1 complex between cytochrome b5 and other redox partner proteins and the second, the characterization by NMR of dynamic properties of selected heme proteins. The research will continue to explore and elucidate, using diverse NMR methods, a wide range of dynamic properties of heme proteins which are likely the key to understanding both their biophysical properties as well as their functions. Biological electron transport is currently one of the most intensely studied of biological processes in which heme proteins play a major role. Knowledge of the structures and dynamic motions of these important molecules is essential in understanding the processes so essential to life.