title: Reactivity with ubiquinone of quinoprotein D-glucose dehydrogenase from Gluconobacter suboxydans.
abstract: D-Glucose dehydrogenase is a pyrroloquinoline quinone-dependent oxidoreductase linked to the respiratory chain of a wide variety of bacteria. There is a controversy as to whether the glucose dehydrogenase is linked to the respiratory chain via ubiquinone or cytochrome b. In this study, it was shown that the glucose dehydrogenase of Gluconobacter suboxydans has the ability to react directly with ubiquinone. The enzyme purified from the membranes of G. suboxydans was able to react with ubiquinone homologues such as ubiquinone-1, -2, or -6 in detergent solution. Furthermore, in order to demonstrate the reactivity of the enzyme with native ubiquinone, ubiquinone-10, in the native membranous environment, the dehydrogenase was reconstituted together with cytochrome o, the terminal oxidase of the respiratory chain, into a phospholipid bilayer containing ubiquinone-10. The proteoliposomes thus reconstituted exhibited a reasonable glucose oxidase activity, the electron transfer reaction of which was able to generate a membrane potential and a pH gradient. Thus, D-glucose dehydrogenase of G. suboxydans has been demonstrated to donate electrons directly to ubiquinone in the respiratory chain.
authors.affiliation: Department of Agricultural Chemistry, Faculty of Agriculture, Yamaguchi University.
authors.forename: K
authors.initials: K
authors.lastname: Matsushita
authors.forename: E
authors.initials: E
authors.lastname: Shinagawa
authors.forename: O
authors.initials: O
authors.lastname: Adachi
authors.forename: M
authors.initials: M
authors.lastname: Ameyama
mesh_terms: D002237:Carbohydrate Dehydrogenases / Q000378:metabolism*; D003576:Electron Transport Complex IV / Q000302:isolation & purification; D004591:Electrophoresis, Polyacrylamide Gel; D005948:Glucose Dehydrogenases / Q000378:metabolism*; D005949:Glucose Oxidase / Q000378:metabolism; D006088:Gram-Negative Aerobic Bacteria / Q000201:enzymology*; D008051:Lipid Bilayers; D008081:Liposomes / Q000032:analysis; D008564:Membrane Potentials; D011808:Quinone Reductases / Q000032:analysis; D011809:Quinones / Q000032:analysis; D014451:Ubiquinone / Q000378:metabolism*
chemical_list: D008051:Lipid Bilayers; D008081:Liposomes; D011809:Quinones; D014451:Ubiquinone; D002237:Carbohydrate Dehydrogenases; D005948:Glucose Dehydrogenases; D005949:Glucose Oxidase; C033955:glucose dehydrogenase (pyrroloquinoline-quinone); D011808:Quinone Reductases; C038862:cytochrome o oxidase; D003576:Electron Transport Complex IV