title: pH-dependent electron transfer reaction and direct bioelectrocatalysis of the quinohemoprotein pyranose dehydrogenase.
abstract: A pyranose dehydrogenase from Coprinopsis cinerea (CcPDH) is an extracellular quinohemoeprotein, which consists a b-type cytochrome domain, a pyrroloquinoline-quinone (PQQ) domain, and a family 1-type carbohydrate-binding module. The electron transfer reaction of CcPDH was studied using some electron acceptors and a carbon electrode at various pH levels. Phenazine methosulfate (PMS) reacted directly at the PQQ domain, whereas cytochrome c (cyt c) reacted via the cytochrome domain of intact CcPDH. Thus, electrons are transferred from reduced PQQ in the catalytic domain of CcPDH to heme b in the N-terminal cytochrome domain, which acts as a built-in mediator and transfers electron to a heterogenous electron transfer protein. The optimal pH values of the PMS reduction (pH 6.5) and the cyt c reduction (pH 8.5) differ. The catalytic currents for the oxidation of l-fucose were observed within a range of pH 4.5 to 11. Bioelectrocatalysis of CcPDH based on direct electron transfer demonstrated that the pH profile of the biocatalytic current was similar to the reduction activity of cyt c characters.
authors.affiliation: Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan.
authors.forename: Kouta
authors.initials: K
authors.lastname: Takeda
authors.affiliation: Department of Biomaterial Sciences, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Hirotoshi
authors.initials: H
authors.lastname: Matsumura
authors.affiliation: Department of Biomaterial Sciences, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Ishida
authors.affiliation: Department of Environmental and Natural Resource Science, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-8509, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Yoshida
authors.affiliation: Department of Biomaterial Sciences, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Kiyohiko
authors.initials: K
authors.lastname: Igarashi
authors.affiliation: Department of Biomaterial Sciences, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Samejima
authors.affiliation: Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Ohno
authors.affiliation: Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan. Electronic address: nobu1@cc.tuat.ac.jp.
authors.forename: Nobuhumi
authors.initials: N
authors.lastname: Nakamura
mesh_terms: D055162:Biocatalysis; D055664:Electrochemical Techniques; D004579:Electron Transport; D006863:Hydrogen-Ion Concentration
keywords: Carbohydrate-active enzyme; Cellobiose dehydrogenase; Electron transfer; Heme proteins; Pyrroloquinoline quinone