Probing the oxygen binding site of cytochrome c oxidase by cyanide.

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Wilson MT, Antonini G, Malatesta F, Sarti P, Brunori M

Probing the oxygen binding site of cytochrome c oxidase by cyanide.

J Biol Chem. 1994 Sep 30;269(39):24114-9.

PubMed ID

7929065 [ View in PubMed

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Abstract

Cyanide binding to cytochrome c oxidase has been investigated by sequential mixing and rapid scan stopped flow spectroscopy. Double mixing experiments confirm earlier reports that cyanide binds rapidly to partially reduced enzyme species formed in turnover. The absorbance/time/wavelength matrices, captured during the onset of cyanide inhibition of cytochrome c oxidase by rapid scan stopped flow, were analyzed by singular value decomposition and the spectral contributions of the chromophores separated. Examination of the time courses and amplitudes of the spectral signals provide evidence that entry of a single (1-1.3) electron into the enzyme is sufficient to trigger rapid cyanide binding. This electron resides predominantly on the cytochrome a/CuA pair in the inhibited enzyme. In addition, although cytochrome a3 remains oxidized, it does not appear to be the site for the initial inhibitory binding of cyanide. Our data suggest that CuB2+ is the initial binding site.

DrugBank Data that Cites this Article

Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
Oxygen	Cytochrome c oxidase subunit 1	Protein	Humans	Unknown	Agonist Activator	Details