Minimal Heterochiral de Novo Designed 4Fe–4S Binding Peptide Capable of Robust Electron Transfer

Ambidoxin is a designed, minimal dodecapeptide consisting of alternating L and D amino acids that binds a 4Fe–4S cluster through ligand–metal interactions and an extensive network of second-shell hydrogen bonds. The peptide can withstand hundreds of oxidation–reduction cycles at room temperature. Ambidoxin suggests how simple, prebiotic peptides may have achieved robust redox catalysis on the early Earth.