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Sulfide inhibition of and metabolism by cytochrome <i>c</i> oxidase

Nicholls, Peter and Marshall, Doug C and Cooper, Chris E and Wilson, Mike T (2013) 'Sulfide inhibition of and metabolism by cytochrome <i>c</i> oxidase.' Biochemical Society Transactions, 41 (5). pp. 1312-1316. ISSN 0300-5127

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<jats:p>Hydrogen sulfide (H2S), a classic cytochrome c oxidase inhibitor, is also an in vitro oxidase substrate and an in vivo candidate hormonal (‘gasotransmitter’) species affecting sleep and hibernation. H2S, nitric oxide (NO) and carbon monoxide (CO) share some common features. All are low-molecular-mass physiological effectors and also oxidase inhibitors, capable of binding more than one enzyme site, and each is an oxidizable ‘substrate’. The oxidase oxidizes CO to CO2, NO to nitrite and sulfide to probable persulfide species. Mitochondrial cytochrome c oxidase in an aerobic steady state with ascorbate and cytochrome c is rapidly inhibited by sulfide in a biphasic manner. At least two successive inhibited species are involved, probably partially reduced. The oxidized enzyme, in the absence of turnover, occurs in at least two forms: the ‘pulsed’ and ‘resting’ states. The pulsed form reacts aerobically with sulfide to form two intermediates, ‘P’ and ‘F’, otherwise involved in the reaction of oxygen with reduced enzyme. Sulfide can directly reduce the oxygen-reactive a3CuB binuclear centre in the pulsed state. The resting enzyme does not undergo such a step, but only a very slow one-electron reduction of the electron-transferring haem a. In final reactivation phases, both the steady-state inhibition of catalysis and the accumulation of P and F states are reversed by slow sulfide oxidation. A model for this complex reaction pattern is presented.</jats:p>

Item Type: Article
Uncontrolled Keywords: compound P; cytochrome aa(3); cytochrome c oxidase; gasotransmitter; sulfide
Subjects: Q Science > QH Natural history > QH301 Biology
Divisions: Faculty of Science and Health
Faculty of Science and Health > Life Sciences, School of
SWORD Depositor: Elements
Depositing User: Elements
Date Deposited: 20 Dec 2014 22:03
Last Modified: 18 Aug 2022 11:04

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