Tryptophan 334 oxidation in bovine cytochrome c oxidase subunit I involves free radical migration

Patrizia Lemma-Gray, Susan T. Weintraub, Christopher A. Carroll, Andrej Musatov, Neal C. Robinson

Research output: Contribution to journalArticle

16 Scopus citations

Abstract

A single tryptophan (W334(I)) within the mitochondrial-encoded core subunits of cytochrome c oxidase (CcO) is selectively oxidized when hydrogen peroxide reacts with the binuclear center. W334(I) is converted to hydroxytryptophan as identified by reversed-phase HPLC-electrospray ionization tandem mass spectrometry analysis of peptides derived from the three SDS-PAGE purified subunits. Total sequence coverage of subunits I, II and III was limited to 84%, 66% and 54%, respectively. W334(I) is located on the surface of CcO at the membrane interface. Two other surface tryptophans within nuclear-encoded subunits, W48(IV) and W19(VIIc), are also oxidized when hydrogen peroxide reacts with the binuclear center (Musatov et al. (2004) Biochemistry 43, 1003-1009). Two aromatic-rich networks of amino acids were identified that link the binuclear center to the three oxidized tryptophans. We propose the following mechanism to explain these results. Electron transfer through the aromatic networks moves the free radicals generated at the binuclear center to the surface-exposed tryptophans, where they produce hydroxytryptophan.

Original languageEnglish (US)
Pages (from-to)437-442
Number of pages6
JournalFEBS Letters
Volume581
Issue number3
DOIs
StatePublished - Feb 6 2007

Keywords

  • Aromatic pathway
  • Cytochrome oxidase
  • Hydrogen peroxide
  • Mass spectrometry
  • Proteolytic digestion
  • Tryptophan oxidation

ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Molecular Biology
  • Genetics
  • Cell Biology

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