Direct detection of coupled proton and electron transfers in human manganese superoxide dismutase

Abstract

Human manganese superoxide dismutase (MnSOD) is an oxidoreductase that uses concerted proton and electron transfers to reduce the levels of superoxide radicals in mitochondria, but mechanistic insights into this process are limited. Here, the authors report neutron crystal structures of Mn3+SOD and Mn2+SOD, revealing changes in the protonation states of key residues in the enzyme active site during the redox cycle.