Electron transfer in ruthenium-modified proteins
- 1 June 1995
- journal article
- research article
- Published by Springer Nature in Journal of Bioenergetics and Biomembranes
- Vol. 27 (3) , 295-302
- https://doi.org/10.1007/bf02110099
Abstract
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) cytochromec and azurin. A driving-force study with the His33 derivatives of cytochromec indicates that the reorganization energy (γ) 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 å−1) that is consistent with predictions of the pathway model.Keywords
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