Description:
<jats:p>Thionitrobenzoate‐modified yeast cytochrome <jats:italic>c</jats:italic> was shown to react with both monomeric and dimeric forms of beef heart cytochrome <jats:italic>c</jats:italic> oxidase through subunit III. This cytochrome <jats:italic>c</jats:italic> derivative was found to inhibit electron transfer in the dimer but not in the monomer. These results are interpreted to show that the high affinity binding site for cytochrome <jats:italic>c</jats:italic> is a cleft at the interface between monomers in the cytochrome <jats:italic>c</jats:italic> oxidase dimer.</jats:p>