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The inhibition of mitochondrial cytochrome oxidase by the gases carbon monoxide, nitric oxide, hydrogen cyanide and hydrogen sulfide: Chemical mechanism and physiological significance

Cooper, CE and Brown, GC (2008) 'The inhibition of mitochondrial cytochrome oxidase by the gases carbon monoxide, nitric oxide, hydrogen cyanide and hydrogen sulfide: Chemical mechanism and physiological significance.' Journal of Bioenergetics and Biomembranes, 40 (5). 533 - 539. ISSN 0145-479X

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Abstract

The four gases, nitric oxide (NO), carbon monoxide (CO), hydrogen sulfide (H2S) and hydrogen cyanide (HCN) all readily inhibit oxygen consumption by mitochondrial cytochrome oxidase. This inhibition is responsible for much of their toxicity when they are applied externally to the body. However, recently these gases have all been implicated, to greater or lesser extents, in normal cellular signalling events. In this review we analyse the chemistry of this inhibition, comparing and contrasting mechanism and discussing physiological consequences. The inhibition by NO and CO is dependent on oxygen concentration, but that of HCN and H2S is not. NO and H2S are readily metabolised by oxidative processes within cytochrome oxidase. In these cases the enzyme may act as a physiological detoxifier of these gases. CO oxidation is much slower and unlikely to be as physiologically important. The evidence for normal physiological levels of these gases interacting with cytochrome oxidase is equivocal, in part because there is little robust data about their steady state concentrations. A reasonable case can be made for NO, and perhaps CO and H2S, inhibiting cytochrome oxidase in vivo, but endogenous levels of HCN seem unlikely to be high enough. © 2008 Springer Science+Business Media, LLC.

Item Type: Article
Subjects: Q Science > QH Natural history > QH301 Biology
Divisions: Faculty of Science and Health > Life Sciences, School of
Depositing User: Jim Jamieson
Date Deposited: 16 Sep 2011 09:01
Last Modified: 19 Aug 2019 17:15
URI: http://repository.essex.ac.uk/id/eprint/704

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