The main goal of the project is to investigate the mechanism of NO and O2 reduction in the flavin dependent non-heme diiron protein (FDP) from E. coli. The project is in collaboration with Margareta Blomberg (NAISS 2026/4-122) and should provide a complementary analysis to the quantum chemical methods. FDP activity and substrate preference vary across species despite a conserved first coordination shell, suggesting second-shell ligands or access channels could potentially influence the enzyme’s properties. Certain variants of E. coli FDP appear to alter substrate specificity significantly, despite no apparent changes to the active site. We aim to investigate the structural changes in the FDP variants outside of the active site by performing classical molecular dynamics.