Chapter 28 Use of ruthenium photoreduction techniques to study electron transfer in cytochrome oxidase.
Ruthenium photoreduction methods are described to study electron transfer from cytochrome c to cytochrome c oxidase and within cytochrome oxidase. Methods are described to prepare a ruthenium cytochrome c derivative Ru-39-Cc, by labeling the single sulfhydryl group on horse K39C with (4-bromomethyl-4'methylbipyridine) (bis-bipyridine)ruthenium(II). The ruthenium complex attached to Cys-39 on the opposite side of the heme crevice does not interfere with the interaction with cytochrome oxidase. Laser flash photolysis of a 1:1 complex between Ru-39-Cc and bovine cytochrome oxidase results in photoreduction of heme c within 1 microsec, followed by electron transfer from heme c to Cu(A) in cytochrome oxidase with a rate constant of 60,000 s(-1) and from Cu(A) to heme a with a rate constant of 20,000 s(-1). A new ruthenium dimer, Ru(2)Z, has been developed to reduce Cu(A) within 1 microsec with a yield of 60%, followed by electron transfer from Cu(A) to heme a and then to the heme a(3)/Cu(B) binuclear center. Methods are described to measure the single-electron reduction of each of the intermediates involved in reduction of oxygen to water by cytochrome oxidase, including P(m), F, O(H), and E.
Geren
Lois
L
Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas, USA.
Durham
Bill
B
Millett
Francis
F
D004579:Electron Transport; D003576:Electron Transport Complex IV / Q000737:chemistry*; D010084:Oxidation-Reduction; D010777:Photochemistry; D012428:Ruthenium / Q000737:chemistry*
D012428:Ruthenium; D003576:Electron Transport Complex IV