Ascorbate Peroxidase Activity of Cytochrome C

Free Radic Res. 2011 Apr;45(4):439-44. doi: 10.3109/10715762.2010.540575. Epub 2010 Dec 3.


The peroxidase-type reactivity of cytochrome c is proposed to play a role in free radical production and/or apoptosis. This study describes cytochrome c catalysis of peroxide consumption by ascorbate. Under conditions where the sixth coordination position at the cytochrome c heme iron becomes more accessible for exogenous ligands (by carboxymethylation, cardiolipin addition or by partial denaturation with guanidinium hydrochloride) this peroxidase activity is enhanced. A reaction intermediate is detected by stopped-flow UV-vis spectroscopy upon reaction of guanidine-treated cytochrome c with peroxide, which resembles the spectrum of globin Compound II species and is thus proposed to be a ferryl species. The ability of physiological levels of ascorbate (10-60 µM) to interact with this species may have implications for mechanisms of cell signalling or damage that are based on cytochrome c/peroxide interactions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis
  • Ascorbic Acid* / metabolism
  • Cardiolipins / metabolism
  • Cattle
  • Cytochrome-c Peroxidase / metabolism*
  • Cytochromes c / metabolism*
  • Free Radicals / metabolism
  • Guanidine / chemistry
  • Guanidine / metabolism
  • Heme / chemistry
  • Horses
  • Hydrogen Peroxide / chemistry
  • Iron / metabolism*
  • Kinetics
  • Methylation
  • Mitochondria, Heart / enzymology*
  • Signal Transduction
  • Spectrum Analysis
  • Yeasts


  • Cardiolipins
  • Free Radicals
  • ferryl iron
  • Heme
  • Cytochromes c
  • Hydrogen Peroxide
  • Iron
  • Cytochrome-c Peroxidase
  • Guanidine
  • Ascorbic Acid