title: Redox properties of quinohemoprotein amine dehydrogenase from Paracoccus denitrificans.
abstract: Paracoccus denitrificans produces two primary enzymes for the amine oxidation, tryptophan-tryptophylquinone (TTQ)-containing methylamine dehydrogenase (MADH) and quinohemoprotein amine dehydrogenase (QH-AmDH). QH-AmDH has a novel cofactor, cysteine tryptophylquinone (CTQ) and two hemes c. In this work, the redox potentials of three redox centers in QH-AmDH were determined by a mediator-assisted continuous-flow column electrolytic spectroelectrochemical technique. Kinetics of the electron transfer from QH-AmDH to three kinds of metalloproteins, amicyanin, cytochrome c(550), and horse heart cytochrome c were examined on the basis of the theory of mediated-bioelectrocatalysis. All these metalloproteins work as a good electron acceptor of QH-AmDH and donate the electron to the terminal oxidase of P. denitrificans, which was revealed by reconstitution of the respiratory chain. These properties are in marked contrast with those of MADH, which shows high specificity to amicyanin. These electron transfer kinetics are discussed in terms of thermodynamics and structural property.
authors.affiliation: Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
authors.forename: Nobutaka
authors.initials: N
authors.lastname: Fujieda
authors.forename: Megumi
authors.initials: M
authors.lastname: Mori
authors.forename: Kenji
authors.initials: K
authors.lastname: Kano
authors.forename: Tokuji
authors.initials: T
authors.lastname: Ikeda
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry*; D003574:Cytochrome c Group / Q000378:metabolism; D004579:Electron Transport; D007700:Kinetics; D010084:Oxidation-Reduction; D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000737:chemistry* / Q000378:metabolism; D010231:Paracoccus denitrificans / Q000201:enzymology*; D021122:Protein Subunits
chemical_list: D001426:Bacterial Proteins; D003574:Cytochrome c Group; D021122:Protein Subunits; C031732:cytochrome C-550; D000587:Oxidoreductases Acting on CH-NH Group Donors; C119497:quinohemoprotein amine dehydrogenase