Molecular and Cellular Biochemistry

, Volume 111, Issue 1, pp 33-40

First online:

Characterization of oxygen free radicals generated during vanadate-stimulated NADH oxidation

  • P. KalyaniAffiliated withDepartment of Biochemistry, Indian Institute of Science
  • , S. VijayaAffiliated withDepartment of Biochemistry, Indian Institute of Science
  • , T. RamasarmaAffiliated withDepartment of Biochemistry, Indian Institute of Science

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The oxidation of NADH and accompanying reduction of oxygen to H2O2 stimulated by polyvanadate was markedly inhibited by SOD and cytochrome c. The presence of decavanadate, the polymeric form, is necessary for obtaining the microsomal enzyme-catalyzed activity. The accompanying activity of reduction of cytochrome c was found to be SOD-insensitive and therefore does not represent superoxide formation. The reduction of cytochrome c by vanadyl sulfate was also SOD-insensitive. In the presence of H2O2 all the forms of vanadate were able to oxidize reduced cytochrome c, which was sensitive to mannitol, tris and also catalase, indicating H202-dependent generation of hydroxyl radicals. Using ESR and spin trapping technique only hydroxyl radicals, but not superoxide anion radicals, were detected during polyvanadate-dependent NADH oxidation.

Key words

vanadate stimulation NADH oxidation hydroxyl radicals superoxide formation SOD-insensitive cytochrome c reduction