Redox behaviour of the haem domain of flavocytochrome c 3 from Shewanella frigidimarina probed by NMR

Miguel Pessanha, Emma L. Rothery, Ricardo O. Louro, David L. Turner, Caroline S. Miles, Graeme A. Reid, Stephen K. Chapman, António V. Xavier, Carlos A. Salgueiro

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


Flavocytochrome c 3 from Shewanella frigidimarina (fcc 3) is a tetrahaem periplasmic protein of 64 kDa with fumarate reductase activity. This work reports the first example of NMR techniques applied to the assignment of the thermodynamic order of oxidation of the four individual haems for such large protein, expanding its applicability to a wide range of proteins. NMR data from partially and fully oxidised samples of fcc 3 and a mutated protein with an axial ligand of haem IV replaced by alanine were compared with calculated chemical shifts, allowing the structural assignment of the signals and the unequivocal determination of the order of oxidation of the haems. As oxidation progresses the fcc 3 haem domain is polarised, with haems I and II much more oxidised than haems III and IV, haem IV being the most reduced. Thus, during catalysis as an electron is taken by the flavin adenosine dinucleotide from haem IV, haem III is eager to re-reduce haem IV, allowing the transfer of two electrons to the active site.

Original languageEnglish
Pages (from-to)185-190
Number of pages6
JournalFEBS Letters
Issue number1-2
Publication statusPublished - 3 Dec 2004


  • Electron transfer protein
  • Flavocytochrome
  • Fumarate respiration
  • Multihaem
  • Nuclear magnetic resonance
  • Shewanella


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