Superoxide generation catalyzed by the ozone-inducible plant peptides analogous to prion octarepeat motif

Ozone-inducible (OI) peptides found in plants contain repeated sequences consisting of a hexa-repeat unit (YGH GGG) repeated 7-9 times in tandem, and each unit tightly binds copper. To date, the biochemical roles for OI peptides are not fully understood. Here, we demonstrated that the hexa-repeat unit from OI peptides behaves as metal-binding motif catalytically active in the O2•--generation. Lastly, possible mechanisms of the reaction and biological consequence of the reactions are discussed by analogy to the action of human prion octarepeat peptides.