The due ferri single chain (DFsc) protein is a de novo designed four-helix bundle designed to mimic the 2-histidine/4-carboxylate active site of natural non-heme diiron enzymes such as methane monooxygenase and ribonucleotide reductase. Previously, a library of eight G4DFsc variants was developed with between two and six His residues at the active site using site-directed mutagenesis to systematically replace each Glu residue. In order to better understand the structure–function relationships of these variants, the reduction–oxidation properties of these diiron proteins were probed using cyclic voltammetry. Understanding how Nature fine-tunes catalytic activity in these proteins can influence the design of artificial proteins for modern applications such as biofuel cells, biosensors, and catalysts. Current work focuses on the cyclic voltammetry of G4DFsc-Fe2 with changes in both pH and anaerobic conditions. Upon addition of the diiron protein or under anaerobic conditions, oxygen-sensitive cyclic voltammetric peaks decrease in current, leading to the conclusion that G4DFsc-Fe2 behaves as an oxygen scavenger, mimicking the behavior of natural non-heme diiron proteins like rubrerythrin.
Cherry Hill, NJ