Reactions of superoxide dismutases with HS-/H2S and superoxide radical anion: An in vitro EPR study

Abstract

Interactions of hydrogen sulfide (HS-/H2S), a reducing signaling species, with superoxide dimutases (SOD) are poorly understood. We applied low-T EPR spectroscopy to examine the effects of HS-/H2S and superoxide radical anion (O-2(-)) on metallocenters of FeSOD, MnSOD, and CuZnSOD. HS-/H2S did not affect FeSOD, whereas active centers of MnSOD and CuZnSOD were open to this agent. Cu2+ was reduced to Cu1+, while manganese appears to be released from MnSOD active center. Untreated and O-2(-) treated FeSOD and MnSOD predominantly show 5 d-electron systems, i.e. Fe3+ and Mn2+. Our study provides new details on the mechanisms of (patho)physiological effects of HS-/H2S.