Subunit Interactions in Cytochrome Oxidase: The Role of Subunit III
Cytochrome c oxidase is an oligomeric membrane protein that catalyzes the oxidation of cytochrome c and the reduction of oxygen to water. The enzyme-mediated proton translocation is also known to be linked to its electron transfer activity either in mitochondria or in artificial phospholipid vesicles (1–4). The protein has been purified from several sources with different procedures, resulting in a variable number of co-purifying subunits (7–12) whose specific functions are still, to a large extent, obscure. According to the latest experimental findings in prokaryotes, however, enzyme activity is linked to the presence of at least the three largest subunits (I, II and III), which are coded by mitochondrial DNA in eukaryotes.
KeywordsCytochrome Oxidase Sedimentation Velocity Sodium Cholate Respiratory Control Ratio Subunit Interaction
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