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PDB 1s24 EBI.jpg
rubredoxin domain ii from pseudomonas oleovorans
Symbol Rubredoxin
Pfam PF00301
Pfam clan CL0045
InterPro IPR004039
SCOP 7rxn

Rubredoxins are a class of low-molecular-weight iron-containing proteins found in sulfur-metabolizing bacteria and archaea. Sometimes rubredoxins are classified as iron-sulfur proteins; however, in contrast to iron-sulfur proteins, rubredoxins do not contain inorganic sulfide. Like cytochromes, ferredoxins and Rieske proteins, rubredoxins participate in electron transfer in biological systems.


The 3-D structures of a number of rubredoxins have been solved. The fold belongs to the α+β class, with 2 α-helices and 2-3 β-strands. Rubredoxin active site contains an iron ion which is coordinated by the sulfurs of four conserved cysteine residues forming an almost regular tetrahedron. This is sometimes denoted as a [1Fe-0S] or an Fe1S0 system, in analogy to the nomenclature for iron-sulfur proteins. While the vast majority of rubredoxins are soluble, there exists a membrane-bound rubredoxin, referred to as rubredoxin A, in oxygenic photoautotrophs.[1]

Rubredoxins perform one-electron transfer processes. The central iron atom changes between the +2 and +3 oxidation states. In both oxidation states, the metal remains high spin, which helps to minimize structural changes. The reduction potential of a rubredoxin is typically in the range +50 mV to -50 mV.

This iron-sulphur protein is an electron carrier, and it is easy to distinguish its metallic centre changes: the oxidized state is reddish (due to a ligand metal charge transfer), while the reduced state is colourless (because the electron transition has an energy of the infrared level, which is imperceptible to the human eye).

Structural representation of a rubredoxin active site.

Rubredoxin in some biochemical reactions[edit]

EC camphor 1,2-monooxygenase [(+)-camphor,reduced-rubredoxin:oxygen oxidoreductase (1,2-lactonizing)]

(+)-bornane-2,5-dione + reduced rubredoxin + O2 = 5-oxo-1,2-campholide + oxidized rubredoxin + H2O

EC alkane 1-monooxygenase (alkane,reduced-rubredoxin:oxygen 1-oxidoreductase)

octane + reduced rubredoxin + O2 = 1-octanol + oxidized rubredoxin + H2O

EC superoxide reductase (rubredoxin:superoxide oxidoreductase)

reduced rubredoxin + superoxide + 2 H+ = rubredoxin + H2O2

EC rubredoxin—NAD+ reductase (rubredoxin:NAD+ oxidoreductase)

reduced rubredoxin + NAD+ = oxidized rubredoxin + NADH + H+

EC rubredoxin—NAD(P)+ reductase (rubredoxin:NAD(P)+ oxidoreductase)

reduced rubredoxin + NAD(P)+ = oxidized rubredoxin + NAD(P)H + H+

See also[edit]


  1. ^ Calderon, R. H., García-Cerdán, J. G., Malnoë, A., Cook, R., Russell, J. J., Gaw, C., Dent, R. M., de Vitry, C. and Niyogi, K. K. (July 2013). "A Conserved Rubredoxin Is Necessary for Photosystem II Accumulation in Diverse Oxygenic Photoautotrophs". The Journal of Biological Chemistry. 288: 26688–26696. doi:10.1074/jbc.M113.487629. PMC 3772215Freely accessible. PMID 23900844. 

Further reading[edit]

  • Stephen J. Lippard, Jeremy M. Berg, Principles of Bioinorganic Chemistry, University Science Books, 1994, ISBN 0-935702-72-5
  • J.J.R. Fraústo da Silva and R.J.P. Williams, The biological chemistry of the elements: The inorganic chemistry of life, 2nd Edition, Oxford University Press, 2001, ISBN 0-19-850848-4

External links[edit]