Enzymes are catalytic proteins with various biological functions. Non-heme diiron enzymes contain two iron ions not bound to a porphyrin ring. Two families within this classification are Ferritin Diiron Oxygenases (FDOs) and Heme-Oxygenase-Like Diiron Oxygenases (HDOs), differing in their diiron co-factor binding structures. We explore the structures of HrmI (an HDO) and Dob3 (an FDO) using X-ray crystallography, revealing dynamic changes in HrmI's active site and optimizing Dob3's crystals for further study.