The proteins are a pair of closely related superoxide dismutase (SOD) enzymes from the Gram positive bacterium, Staphylococcus aureus. SodA is a Mn-specific SOD (MnSOD), which is inactive when loaded with Fe, whereas SodM is a 'cambialistic' SOD (camSOD), which is catalytically active with either Mn or Fe as a cofactor. Their sequences are 75% identical across their 199 amino acid sequences: the crystal structures of each enzyme in each metal-loaded form: Mn-loaded MnSOD SodA: PDB ID 5N56 Fe-loaded MnSOD SodA: PDB ID 6EX3 Mn-loaded camSOD SodM: PDB ID 5N57 Fe-loaded camSOD SodM: PDB ID 6EX4 The resulting structures (all to approximately 2A resolution) showed no significant differences that indicated molecular reasons for the differences in activity. Because of the differences in activity, therefore, the project aimed to compare three forms of these enzymes to determine whether there are any differences in the dynamics of regions of their structure, most notably those within the active site and the putative substrate access route(s).