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  • Title: Effects of mutation of residue I67 on redox-linked protonation processes in yeast cytochrome c oxidase.
    Author: Meunier B, Ortwein C, Brandt U, Rich PR.
    Journal: Biochem J; 1998 Mar 15; 330 ( Pt 3)(Pt 3):1197-200. PubMed ID: 9494085.
    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.
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