Characterization of cytochrome a1 that functions as a ubiquinol oxidase in Acetobacter aceti

Cytochrome a1, a terminal oxidase specific for ethanol oxidation in Acetobacter aceti, comprises four subunits (55, 35, 22 and 13 kDa) and possesses heme b, heme a and a Cu ion. Cytochrome a1 plays the role of a ubiquinol oxidase and is structurally and functionally parallel to O type ubiquinol oxidase of E. coli. The structural similarities between cytochrome a1 and cytochrome C oxidase aa3 classify the two as members of the superfamily of heme-copper oxidases.