Our work focusses on biological nitrogen fixation by Nitrogenase, on metalloenzymes and integral membrane proteins of bacterial and archaeal respiratory systems (Andrade/Einsle/Wohlwend), the working mechanism and regulation of medically relevant membrane proteins and complexes and their defects leading to pathologies (Hunte), bacterial antibiotic resistance factors and viral and bacterial proteins bound to their targets or inhibitors, and their interactions with glycans (Stehle/Zocher), human S100 proteins involved in nutritional immunity, USP18 enforcing the endogenous antiviral interferon response, and the respiratory complex NQR of V. cholerae (Fritz), DNA Polymerases with artificial substrates (Benz), and on multi-domain components of the sarcomeric filamentous protein titin and their binding to the E3 ubiquitin ligase MuRF1 and the central myosin rod-domain (Mayans).