The reaction of ascorbic acid with different heme iron redox states of myoglobin. Antioxidant and prooxidant aspects

Cecilia R Giulivi, Enrique Cadenas

Research output: Contribution to journalArticle

101 Scopus citations

Abstract

The interaction of ascorbate with different heme iron redox states of myoglobin (ferrylmyoglobin, FeIV=O; metmyoglobin, FeIII; and oxymyoglobin FeIIO2) was examined by e.s.r. and absorption spectroseopy. The reaction of ascorbate with ferryl- or met-myoglobin resulted in ascorbyl radical production. The interaction of ascorbate with oxymyoglobin proceeded with formation of ascorbyl radical, hydrogen peroxide, and an overall oxidation of oxymyoglobin to metmyoglobin. The latter reaction proceeded via an oxoferryl complex intermediate - corresponding to ferrylmyoglobin and identified by treatment of the reaction mixture with Na2S. These observations are consistent with a concerted electron transfer mechanism, whereby the two electrons required for the reduction of oxygen to hydrogen peroxide are donated by ascorbic acid and the heme iron. The antioxidant and prooxidant aspects of these redox transitions are discussed in terms of their kinetic properties.

Original languageEnglish (US)
Pages (from-to)287-290
Number of pages4
JournalFEBS Letters
Volume332
Issue number3
DOIs
StatePublished - Oct 18 1993
Externally publishedYes

Keywords

  • Antioxidant
  • Ascorbate
  • Ascorbyl radical
  • Ferrylmyoglobin
  • Oxymyoglobin

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Molecular Biology

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