Michael I. Verkhovsky

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Cytochrome bd is a respiratory quinol: O₂ oxidoreductase found in many prokaryotes, including a number of pathogens. The main bioenergetic function of the enzyme is the production of a proton motive force by the vectorial charge transfer of protons. The sequences of cytochromes bd are not homologous to those of the other respiratory oxygen reductases, i.e.,(More)
Cytochrome c oxidase catalyzes most of the biological oxygen consumption on Earth, a process responsible for energy supply in aerobic organisms. This remarkable membrane-bound enzyme also converts free energy from O(2) reduction to an electrochemical proton gradient by functioning as a redox-linked proton pump. Although the structures of several oxidases(More)
3.3. Electron Tunneling between the Heme Groups 7068 4. Catalytic Cycle and States of the Binuclear Center 7069 4.1. O2 Binding and Bond Splitting 7069 4.2. Intermediate States of the Binuclear Center 7071 4.2.1. States PM, PR, and F 7071 4.2.2. Metastable States of the Binuclear Center 7072 4.2.3. Bridging Ligand in the Binuclear Site 7072 5. Proton(More)
Membrane-bound cytochrome c oxidase catalyzes cell respiration in aerobic organisms and is a primary energy transducer in biology. The two halves of the catalytic cycle may be studied separately: in an oxidative phase, the enzyme is oxidized by O(2), and in a reductive phase, the oxidized enzyme is reduced before binding the next O(2) molecule. Here we show(More)
Cytochrome c oxidase (CcO) is a terminal protein of the respiratory chain in eukaryotes and some bacteria. It catalyzes most of the biologic oxygen consumption on earth done by aerobic organisms. During the catalytic reaction, CcO reduces dioxygen to water and uses the energy released in this process to maintain the electrochemical proton gradient by(More)
The Na+-translocating NADH:ubiquinone oxidoreductase (Na+-NQR) is a component of the respiratory chain of various bacteria. This enzyme is an analogous but not homologous counterpart of mitochondrial Complex I. Na+-NQR drives the same chemistry and also uses released energy to translocate ions across the membrane, but it pumps Na+ instead of H+. Most likely(More)
Recent time-resolved optical and electrometric experiments have provided a sequence of events for the proton-translocating mechanism of cytochrome c oxidase. These data also set limits for the mechanistic, kinetic, and thermodynamic parameters of the proton pump, which are analysed here in some detail. The analysis yields limit values for the pK of the(More)
Aerobic life is based on a molecular machinery that utilizes oxygen as a terminal electron sink. The membrane-bound cytochrome c oxidase (CcO) catalyzes the reduction of oxygen to water in mitochondria and many bacteria. The energy released in this reaction is conserved by pumping protons across the mitochondrial or bacterial membrane, creating an(More)
We have studied the flow-flash reaction of fully reduced cytochrome c oxidase with a high concentration of oxygen (1 mM), recording the first 200 microseconds of the reaction at a number of wavelengths between 400 and 455 nm. This approach has allowed us to observe kinetic phases with time constants of 8 and 32 microseconds and to separate their spectra.(More)
The reaction of cytochrome c oxidase with dioxygen has been studied by means of time-resolved measurements of electrical membrane potential (DeltaPsi). Microsecond time resolution was achieved by starting with the CO-inhibited enzyme, which was photolyzed after addition of oxygen. The time course of the reaction could be fitted by using a five-step(More)