The unusual redox properties of flavocytochrome P450BM3 flavodoxin domain

S C Hanley, T W B Ost, S Daff

Research output: Contribution to journalArticlepeer-review

Abstract

Flavocytochrome P450 BM3 FMN domain is unique among the family of flavodoxins and homologues, in not forming a stable neutral blue FMN semiquinone radical. Anaerobic, one-electron reduction of the isolated domain over the pH 7-9.5 range showed that it forms an anionic red semiquinone that disproportionates slowly (0.014 s(-1) at pH 7). The rate of disproportionation decreased at higher pH, indicating that protonation of the anionic semiquitione is an important feature of the mechanism. The reduction potential for the oxidised-semiquinone couple was determined to be -240 mV and was largely independent of pH. The semiquinone appears, therefore, to be kinetically trapped by a slow protonation event, enabling it to act as a low-potential electron donor to the P450 heme. (C) 2004 Elsevier Inc. All rights reserved.

Original languageEnglish
Pages (from-to)1418-1423
Number of pages6
JournalBiochemical and Biophysical Research Communications
Volume325
Issue number4
DOIs
Publication statusPublished - 24 Dec 2004

Keywords

  • reduction potential
  • electron transfer
  • electrochemistry
  • semiquinone
  • disproportionation
  • rate constant
  • ELECTRON-TRANSFER
  • FLAVOPROTEIN DOMAIN
  • CYTOCHROME P450BM-3
  • FMN-BINDING
  • RESOLUTION
  • REDUCTASE
  • P-450
  • POTENTIALS
  • MECHANISM
  • HEME

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