Ethanol Oxidase Respiratory Chain of Acetic Acid Bacteria. Reactivity with Ubiquinone of Pyrroloquinoline Quinone-dependent Alcohol Dehydrogenases Purified fromAcetobacter acetiandGluconohacter suhoxydans

Abstract
Membrane-bound, pyrroloquinoline quinone-dependent, alcohol dehydrogenase functions as the primary dehydrogenase in the respiratory chain of acetic acid bacteria. In this study, an ability of the enzyme to directly react with ubiquinone was investigated in alcohol dehydrogenases purified from both Acetobacter aceti and Gluconobacter suboxydans by two different approaches. First, it was shown that the enzymes are able to reduce natural ubiquinones, ubiquinone-9 or -t0, in a detergent solution as well as a soluble short-chain homologue, ubiquinone-I. In order to show the reactivity of the enzyme with natural ubiquinone in a native membrane environment, furthermore, alcohol dehydrogenase was reconstituted into proteoliposomes together with natural ubiquinone and a terminal ubiquinol oxidase. The reconstitution was done by binding the detergent-free dehydrogenase at room temperature to proteoliposomes that had been prepared in advance from a ubiquinol oxidase and phospholipids containing ubiquinone by deterge...