Faculty Collaboration Database

Bicarbonate enhances the peroxidase activity of Cu,Zn-superoxide dismutase. Role of carbonate anion radical. J Biol Chem 1999 Oct 01;274(40):28233-9

Date

09/25/1999

Pubmed ID

10497178

DOI

10.1074/jbc.274.40.28233

Scopus ID

2-s2.0-0033214459 (requires institutional sign-in at Scopus site)   88 Citations

Abstract

We examined the effect of bicarbonate on the peroxidase activity of copper-zinc superoxide dismutase (SOD1), using the nitrite anion as a peroxidase probe. Oxidation of nitrite by the enzyme-bound oxidant results in the formation of the nitrogen dioxide radical, which was measured by monitoring 5-nitro-gamma-tocopherol formation. Results indicate that the presence of bicarbonate is not required for the peroxidase activity of SOD1, as monitored by the SOD1/H(2)O(2)-mediated nitration of gamma-tocopherol in the presence of nitrite. However, bicarbonate enhanced SOD1/H(2)O(2)-dependent oxidation of tocopherols in the presence and absence of nitrite and dramatically enhanced SOD1/H(2)O(2)-mediated oxidation of unsaturated lipid in the presence of nitrite. These results, coupled with the finding that bicarbonate protects against inactivation of SOD1 by H(2)O(2), suggest that SOD1/H(2)O(2) oxidizes the bicarbonate anion to the carbonate radical anion. Thus, the amplification of peroxidase activity of SOD1/H(2)O(2) by bicarbonate is attributed to the intermediary role of the diffusible oxidant, the carbonate radical anion. We conclude that, contrary to a previous report (Sankarapandi, S., and Zweier, J. L. (1999) J. Biol. Chem. 274, 1226-1232), bicarbonate is not required for peroxidase activity mediated by SOD1 and H(2)O(2). However, bicarbonate enhanced the peroxidase activity of SOD1 via formation of a putative carbonate radical anion. Biological implications of the carbonate radical anion in free radical biology are discussed.

Author List

Goss SP, Singh RJ, Kalyanaraman B

Author

Balaraman Kalyanaraman PhD Professor in the Biophysics department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Animals
Bicarbonates
Cattle
Chromatography, High Pressure Liquid
Electron Spin Resonance Spectroscopy
Enzyme Activation
Free Radicals
Kinetics
Peroxidases
Superoxide Dismutase
Vitamin E