Rhodobacter sphaeroides haem protein: A novel cytochrome with nitric oxide dioxygenase activity

Bor-Ran Li, J. L.Ross Anderson, Christopher G. Mowat, Caroline S. Miles, Graeme A. Reid, Stephen K. Chapman*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Rhodobacter sphaeroides produces a novel cytochrome, designated as SHP (sphaeroides haem protein), that is unusual in having asparagine as a redox-labile haem ligand. The gene encoding SHP is contained within an operon that also encodes a DHC (dihaem cytochrome c) and a membrane-associated cytochrome b. DHC and SHP have been shown to have high affinity for each other at low ionic strength (K d = 0.2 μM), and DHC is able to reduce SHP very rapidly. The reduced form of the protein, SHP 2+ (reduced or ferrous SHP), has high affinity for both oxygen and nitric oxide (NO). it has been shown that the oxyfeffous form, SHP 2+ -O 2 (oxygen-bound form of SHP), reacts rapidly with NO to produce nitrate, whereas SHP 2+ -NO (the NO-bound form of SHP) will react with superoxide with the same product formed. it is therefore possible that SHP functions physiologically as a nitric oxide dioxygenase, protecting the organism against NO poisoning, and we propose a possible mechanism for this process.

Original languageEnglish
Pages (from-to)992-995
Number of pages4
JournalBiochemical Society Transactions
Issue number5
StatePublished - 1 Oct 2008


  • C-type cytochrome
  • Crystal structure
  • Dihaem cytochrome c
  • Nitric oxide dioxygenase
  • Rhodobacter sphaeroides
  • Sphaeroides haem protein

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