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A Re-Examination Of The Reactions Of Cyanide With Cytochrome C Oxidase, M. G. Jones, D. Bickar, M. T. Wilson, M. Brunori, A. Colosimo, P. Sarti
A Re-Examination Of The Reactions Of Cyanide With Cytochrome C Oxidase, M. G. Jones, D. Bickar, M. T. Wilson, M. Brunori, A. Colosimo, P. Sarti
Chemistry: Faculty Publications
Experiments were performed to examine the cyanide-binding properties of resting and pulsed cytochrome c oxidase in both their stable and transient turnover states. Inhibition of the oxidation of ferrocytochrome c was monitored as a function of cyanide concentration. Cyanide binding to partially reduced forms produced by mixing cytochrome c oxidase with sodium dithionite was also examined. A model is presented that accounts fully for cyanide inhibition of the enzyme, the essential feature of which is the rapid, tight, binding of cyanide to transient, partially reduced, forms of the enzyme populated during turnover. Computer fitting of the experimentally obtained data to …
Carbon Monoxide-Driven Reduction Of Ferric Heme And Heme Proteins, D. Bickar, C. Bonaventura, J. Bonaventura
Carbon Monoxide-Driven Reduction Of Ferric Heme And Heme Proteins, D. Bickar, C. Bonaventura, J. Bonaventura
Chemistry: Faculty Publications
Oxidized cytochrome c oxidase in a carbon monoxide atmosphere slowly becomes reduced as shown by changes in its visible spectra and its reactivity toward oxygen. The 'autoreduction' of cytochrome c oxidase by this procedure has been used to prepare mixed valence hybrids. We have found that this process is a general phenomenon for oxygen-binding heme proteins, and even for isolated hemin in basic aqueous solution. This reductive reaction may have physiological significance. It also explains why oxygen-binding heme proteins become oxidized much more slowly and appear to be more stable when they are kept under a CO atmosphere. Oxidized α …