Effects of mutation of residue I67 on redox-linked protonation processes in yeast cytochrome c oxidase
- 15 March 1998
- journal article
- Published by Portland Press Ltd. in Biochemical Journal
- Vol. 330 (3) , 1197-1200
- https://doi.org/10.1042/bj3301197
Abstract
We describe effects of a mutation, Ile-67 → Asn, in subunit I of yeast cytochrome c oxidase on redox-linked protonation processes within the protein. The mutation lowers the midpoint potential of haem a and weakens its pH dependency, but has little effect on the potential of haem a3. The residue is close to a conserved glutamate (Glu-243) in the crystal structure. We propose that protonation of Glu-243 is redox-linked to haem a, that Asn-167 perturbs its pK and that redox-linked protonation in this location is essential for the catalytic reactions of the binuclear centre. These proposals are discussed in terms of a ‘glutamate trap’ mechanism for proton translocation in the haem/copper oxidases.Keywords
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