Activation volumes for intramolecular electron transfer in Escherichia coli cytochrome bo3

Erin Ching, Robert B. Gennis, Randy W. Larsen

Research output: Contribution to journalArticlepeer-review

Abstract

In this report we describe the activation volumes associated with the heme-heme electron transfer (ET) and CO rebinding to the binuclear center subsequent to photolysis of the CO-mixed-valence derivative of Escherichia coli cytochrome bo3 (Cbo). The activation volumes associated with the heme-heme ET (k=1.2×105 s-1), and CO rebinding (k=57 s-1) are found to be +27.4 ml/mol and -2.6 ml/mol, respectively. The activation volume associated with the rebinding of CO is consistent with previous Cu X-ray absorption studies of Cbo where a structural change was observed at the CuB site (loss of a histidine ligand) due to a change in the redox state of the binuclear center. In addition, the volume of activation for the heme-heme ET was found to be quite distinct from the activation volumes obtained for heme-heme ET in bovine heart Cytochrome c oxidase. Differences in mechanisms/pathways for heme b/heme o3 and heme a/heme a3 ET are suggested based on the associated activation volumes and previously obtained Marcus parameters.

Original languageEnglish (US)
Pages (from-to)81-85
Number of pages5
JournalFEBS Letters
Volume527
Issue number1-3
DOIs
StatePublished - Sep 11 2002

Keywords

  • Activation volume
  • Cytochrome bo
  • Cytochrome c oxidase
  • Electron transfer
  • High pressure
  • Mixed valence

ASJC Scopus subject areas

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

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