Use of a metallopeptide-based mimic provides evidence for a proton-coupled electron-transfer mechanism for superoxide reduction by nickel-containing superoxide dismutase.

Sneaky little SOD! A metallopeptide-based mimic of nickel-containing superoxide dismutase was used to probe the mechanism of superoxide reduction by the metalloenzyme. Kinetic studies suggest a proton-coupled electron-transfer mechanism; large H/D kinetic isotope effects (KIE) are observed. XAS studies suggest the transferred H-atom is in the form of a Ni(II) -S(H)-Cys moiety.