Peroxidase properties of extracellular superoxide dismutase role of uric acid in modulating in vivo activity

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Abstract

Objective - The cytosolic form of Cu/Zn-containing superoxide dismutase (SOD1) has peroxidase activity, with H2O2 used as a substrate to oxidize other molecules. We examined peroxidase properties of the extracellular form of SOD (SOD3), a major isoform of SOD in the vessel wall, by using recombinant SOD3 and an in vivo model of atherosclerosis. Methods and Results - In the presence of HCO3-, SOD3 reacted with H2O2 to produce a hydroxyl radical adduct of the spin trap 5-diethoxyphosphoryl-5methyl-1-pyrroline N-oxide (DEMPO). SOD1 and SOD3 were inactivated by H2O2 in a dose- and time-dependent fashion, and this was prevented by physiological levels of uric acid. To examine the in vivo role of uric acid on SOD1 and SOD3, control and apolipoprotein E-deficient (ApoE-/-) mice were treated with oxonic acid, which inhibits urate metabolism. This treatment increased plasma levels of uric acid in control and ApoE-/- mice by ≈3-fold. Although increasing uric acid levels did not alter aortic SOD1 and SOD3 protein expression, aortic SOD1 and SOD3 activities were increased by 2- to 3-fold in aortas from ApoE-/- mice but not in aortas from control mice. Conclusions - These studies show that SOD1 and SOD3 are partially inactivated in atherosclerotic vessels of ApoE-/- mice and that levels of uric acid commonly encountered in vivo may regulate vascular redox state by preserving the activity of these enzymes.

Original languageEnglish (US)
Pages (from-to)1402-1408
Number of pages7
JournalArteriosclerosis, thrombosis, and vascular biology
Volume22
Issue number9
DOIs
Publication statusPublished - Sep 1 2002
Externally publishedYes

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Keywords

  • Atherosclerosis
  • Hydrogen peroxide
  • Peroxidase activity
  • Superoxide dismutase
  • Uric acid

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine

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