Definition of the Interaction Domain and Electron Transfer Route between Cytochrome c and Cytochrome Oxidase.

The reaction between cytochrome c () and cytochrome c oxidase (CcO) was studied using horse cytochrome c derivatives labeled with ruthenium trisbipyridine at Cys 39 (Ru-39-). Flash photolysis of a 1:1 complex between Ru-39- and bovine CcO at a low ionic strength resulted in the electron transfer from photoreduced heme c to Cu with an intracomplex rate constant of = 6 × 10 s. The K13A, K72A, K86A, and K87A Ru-39- mutants had nearly the same value but bound much more weakly to bovine CcO than wild-type Ru-39-, indicating that lysines 13, 72, 86, and 87 were involved in electrostatic binding to CcO, but were not involved in the electron transfer pathway.

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.

Double-pionic fusion of nuclear systems and the "ABC" effect: approaching a puzzle by exclusive and kinematically complete measurements.

The ABC effect-a puzzling low-mass enhancement in the pipi invariant mass spectrum, first observed by Abashian, Booth, and Crowe-is well known from inclusive measurements of two-pion production in nuclear fusion reactions. Here we report on the first exclusive and kinematically complete measurements of the most basic double-pionic fusion reaction pn-->dpi;{0}pi;{0} at beam energies of 1.03 and 1.

Proton-dependent electron transfer from CuA to heme a and altered EPR spectra in mutants close to heme a of cytochrome oxidase.

Eukaryotic cytochrome c oxidase (CcO) and homologous prokaryotic forms of Rhodobacter and Paraccocus differ in the EPR spectrum of heme a. It was noted that a histidine ligand of heme a (H102) is hydrogen bonded to serine in Rhodobacter (S44) and Paraccocus CcOs, in contrast to glycine in the bovine enzyme. Mutation of S44 to glycine shifts the heme a EPR signal from g(z) = 2.