title: Identification and characterization of hydroxyquinone hydratase activities from Sphingobium chlorophenolicum ATCC 39723.
abstract: Hydroxyquinol, a common metabolite of aromatic compounds, is readily auto-oxidized to hydroxyquinone. Enzymatic activities that metabolized hydroxyquinone were observed from the cell extracts of Sphingobium chlorophenolicum ATCC 39723. An enzyme capable of transforming hydroxyquinone was partially purified, and its activities were characterized. The end product was confirmed to be 2,5-dihydroxyquinone by comparing UV/Vis absorption spectra, electrospray mass spectra, and gas chromatography-mass spectra of the end product and the authentic compound. We have proposed that the enzyme adds a H2O molecule to hydroxyquinone to produce 2,5-dihydroxycyclohex-2-ene-1, 4-dione, which spontaneously rearranges to 1, 2,4,5-tetrahydroxybenzene. The latter is auto-oxidized by O2 to 2,5-dihydroxyquinone. The proposed pathway was supported by the overall reaction stoichiometry. Thus, the transformation of hydroxyquinol to 2,5-dihydroxyquinone involves two auto-oxidation of quinols and one enzymatic reaction catalyzed by a hydratase. The specific enzymatic step did not require O2, further supporting the assignment as a hydratase. To our knowledge, this is the first identification of a quinone hydratase, enhancing the knowledge on microbial metabolism of hydroxyquinone and possibly leading to the development of enzymatic method for the production of 2,5-dihydroxyquinone, a widely used chemical in various industrial applications.
authors.affiliation: School of Molecular Biosciences, Washington State University, Pullman, WA99164-4234, USA.
authors.forename: Jan
authors.initials: J
authors.lastname: Bohuslavek
authors.forename: Suchart
authors.initials: S
authors.lastname: Chanama
authors.forename: Ronald L
authors.initials: RL
authors.lastname: Crawford
authors.forename: Luying
authors.initials: L
authors.lastname: Xun
mesh_terms: D016227:Benzoquinones / Q000737:chemistry / Q000378:metabolism*; D001673:Biodegradation, Environmental; D006836:Hydro-Lyases / Q000302:isolation & purification / Q000378:metabolism*; D010416:Pentachlorophenol / Q000378:metabolism; D021241:Spectrometry, Mass, Electrospray Ionization; D042301:Sphingomonadaceae / Q000201:enzymology*
chemical_list: D016227:Benzoquinones; C412333:2,5-dihydroxy-1,4-benzoquinone; C054093:2-hydroxy-1,4-benzoquinone; D010416:Pentachlorophenol; D006836:Hydro-Lyases