Intramolecular Electron-Transfer between Ru(i) and Ru(iii) and the Heme Iron of Cytochrome-C Labeled with Ruthenium(ii) Polypyridine Complexes

by Heacock II, Donald H.; Harris, Michele Ruth Rogers; Durham, Bill; Millett, Francis Spencer

The rates of intramolecular electron transfer between Ru(III) and Fe(II) of three derivatives of cytochrome c labeled at lysines 86, and and 7 with Ru(4,4'-dicarboxybipyridine)(bipyridine)2(2+) have been measured. The respective rate constants are 1.1x10(5), 1.3x10(5) and 6x10(5) s(-1). Corresponding rates of electron transfer between Ru(I) and Fe(III) of these derivatives have also been measured. The respective rate constants are 3.3 x 10(5), 5.7x10(5) and 1x10(6) s(-1). In addition the rate constant for a derivative labeled at lysine 87 was determined to be 2.7x10(5) s(-1). The two sets of rate constants appeared to be correlated with each other with respect to the location of the ruthenium label. The Ru(I) rate constants are 2-3 times larger than the corresponding Ru((III) rate constants. Preliminary analysis suggests that the observed rate constants are not consistent with the large free energy of reaction expected for Ru(I).

Journal
Inorganica Chimica Acta
Volume
226
Issue
42737
Year
1994
Start Page
129
ISBN/ISSN
1873-3255; 0020-1693
DOI
10.1016/0020-1693(94)04078-8