Cyanide inhibition of cytochrome c oxidase. A rapid-freeze e.p.r. investigation
- 15 December 1984
- journal article
- research article
- Published by Portland Press Ltd. in Biochemical Journal
- Vol. 224 (3), 829-837
- https://doi.org/10.1042/bj2240829
Abstract
The inhibition of cytochrome c oxidase by cyanide, starting either with the resting or the pulsed enzyme, was studied by rapid-freeze quenching followed by quantitative e.p.r. It is found that a partial reduction of cytochrome oxidase by transfer of 2 electron equivalents from ferrocytochrome c to cytochrome a and CuA will induce a transition from a closed to an open enzyme conformation, rendering the cytochrome a3-CuB site accessible for cyanide binding, possibly as a bridging ligand. A heterogeneity in the enzyme is observed in that an e.p.r. signal from the cytochrome a3 3+-HCN complex is only found in 20% of the molecules, whereas the remaining cyanide-bound a3-CuB sites are e.p.r.-silent.This publication has 20 references indexed in Scilit:
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