Research at the Unit of Bioenergetics, Structural Biology and Mechanisms aims at understanding how the different levels of organisation of biological macromolecules define their function. We principally study soluble and membrane protein architectures, involved in the biological processes of bioenergetics, oxidative stress, and genome control and repair. Extensive use is made of approaches combining biochemistry, molecular biology and genetics, together with structural and spectroscopic methods. This combination of techniques can provide information on a wide range of different scales. At the atomic scale, EPR, Raman and infrared absorption spectroscopy yield information on the detailed structure of protein active sites, and how this structure is related to protein function. Time-resolved techniques may be used for determining the reaction pathways in these active sites. At a molecular scale, the structure of the protein and of the interaction surfaces necessary for the formation of active complexes may be obtained from NMR spectroscopy and crystallography. Finally at a multi-molecular scale, studying the composition, the structure and the dynamics of multi-subunit protein assemblies yields information on the regulation of complex processes in vivo.