Superoxide reactivates nitric oxide-inhibited catalase

Y. S. Kim, S. Han

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


Catalase binds nitric oxide (NO) to generate ferricatalase-NO, an inhibited form of the enzyme. Superoxide (O2-) is also an inactivator of the enzyme. We found, however, that O2- efficiently converted the inhibited ferricatalase-NO to the active ferricatalase without producing detectable intermediates. The reaction slowed down when O2- was disproportionated to H2O2 and O2 by superoxide dismutase, but H2O2 could displace the heme-bound NO slowly to regenerate ferricatalase. Reactivation was observed even under simultaneous generation of NO and O2-, suggesting that ferricatalase-NO reacts with O2- fast enough to compete with the rapid reaction of O2- and NO. Formation of peroxynitrite by the simultaneous generation of NO and O2- was only partially inhibited by ferricatalase, presumably due to slow binding of NO to catalase in comparison with the reaction of NO and O2-.

Original languageEnglish (US)
Pages (from-to)1269-1271
Number of pages3
JournalBiological Chemistry
Issue number12
StatePublished - 2000
Externally publishedYes


  • Catalase
  • Nitric oxide
  • Superoxide

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Clinical Biochemistry


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