Electron transfer in ruthenium-modified proteins

J Bioenerg Biomembr. 1995 Jun;27(3):295-302. doi: 10.1007/BF02110099.


Photochemical techniques have been used to measure the kinetics of intramolecular electron transfer in Ru(bpy)2(im)(His)2(+)-modified (bpy = 2,2'-bipyridine; im = imidazole) cytochrome c and azurin. A driving-force study with the His33 derivatives of cytochrome c indicates that the reorganization energy (lambda) for Fe2+-->Ru3+ ET reactions is 0.8 eV. Reductions of the ferriheme by either an excited complex, *Ru2+, or a reduced complex, Ru+, are anomalously fast and may involve formation of an electronically excited ferroheme. The distance dependence of Fe2+-->Ru3+ and Cu+-->Ru3+ electron transfer in 12 different Ru-modified cytochromes and azurins has been analyzed using a tunneling-pathway model. The ET rates in 10 of the 12 systems exhibit an exponential dependence on metal-metal separation (decay constant of 1.06 A-1) that is consistent with prediction of the pathway model.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.
  • Review

MeSH terms

  • Azurin / chemistry*
  • Azurin / drug effects
  • Azurin / metabolism*
  • Cytochrome c Group / chemistry*
  • Cytochrome c Group / drug effects
  • Cytochrome c Group / metabolism*
  • Electron Transport*
  • Histidine
  • Kinetics
  • Models, Theoretical
  • Photochemistry / methods
  • Protein Structure, Secondary*
  • Ruthenium / pharmacology*
  • Thermodynamics


  • Cytochrome c Group
  • Azurin
  • Histidine
  • Ruthenium