Kinetic trapping of oxygen in cell respiration

Article Abstract:

Fast electron transfer between the heme groups is the important factor in attaining high affinity for oxygen in cell respiration. Cytochrome bo3 and oo3 were used to analyze the heme-heme electron transfer reaction. The reduction in heme-heme electron transfer rate in the respiratory heme-copper oxidase from Escherichia coli causes reduction in enzyme steady state affinity for oxygen. The weak binding of O2 to respiratory heme-copper oxidase is due to the kinetic trapping of O2 during fast reaction of O2 in the heme-copper core.

Physiological aspects, Oxygen, Oxygen transport, Tissue respiration, Heme

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Proton translocation by cytochrome c oxidase

Article Abstract:

In mitochondria and some bacterial, cell respiration is catalyzed by cytochrome c oxidase. The catalytic cycle comprises a reductive phases and an oxidative phase. Time-resolved measurements of membrane potential indicate that half of the electrical charges caused by proton-pumping actually traverse the membrane during reduction, after a preceding oxidative phase. Proton translocation was found to occur during reduction.

Bacteria, Mitochondria, Cytochrome c

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Proton-coupled electron transfer drives the proton pump of cytochrome c oxidase

Article Abstract:

Cytochrome c oxidase is a key component of the respiratory chain, which harnesses dioxygen as a sink for electrons and links [O.sub.2] reduction to proton pumping. Electrons from cytochrome c are transferred sequentially to the [O.sub.2] reduction site of cytochorome c oxidase through two other metal centres that is coupled to vectorial proton transfer across the membrane by a hitherto unknown mechanism.

Science & research, Electron transport, Protons, Cytochrome oxidase

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