Ru-Modified Proteins

Flash photolysis and pulse radiolysis techniques have been developed to study Fe Ru ET in Ru-modified proteins [21,26,27]. A method that allows study of electron transfer from a surfaee ajRu(IIIXhistidine) to a protein redox center is outlined in the Scheme [21]. The ET reaction is initiated by photogenerated... 

Another attractive way to control ET rates in protein-protein complexes is by variations in electronic coupling. Conformational changes conceivably could form or break up pathways involving H-bonds or through-space interactions. Examination of potential ET pathways in selected protein-protein complexes is underway in collaboration with Beratan and Onuchic [76]. The foundation we have built in our investigations on Ru-modified proteins should be helpful in this work. 

The Ru-modified proteins give no evidence for DEPC modification, consistent with attachment of Ru at His59. Furthermore, a shoulder is observed in the Ru(III)Cu(lI) spectrum at 300 nm (e 2000 cm ), which is in agreement... 

A final point is that electron transfer reactions of the Ru modified proteins are generally slow when compared with the protein-protein reactions or with simple model systems. The reasons for this discrepancy are far from clear. Likely, explanations include an... 

Figure 8 Distance dependence of observed ET rates in CcO ( ) and the PRC ( ). The solid line shows the average distance dependence found for driving-force-optimized ET in Ru-modified proteins (fi = 1.1 A )...

A great deal of work on Ru-modified proteins has employed the Ru(bpy)2(im) (HisX) " (bpy = 2,2 -bipyridine im = imidazole) label [16, 21, 26] (Figure 2). In addition to favorable ET properties, these Ru-bpy complexes have long-lived, luminescent metal-to-ligand charge-transfer excited states that can be prepared with... 

ET in a Ru-modified protein was first measured in Ru(NH3)5(His33) +-ferrieyto-ehrome c [28]. The rate of Ru + to Fe + electron transfer over a distance of 18 A at... 

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