title: Purification and characterization of laccases from the white-rot basidiomycete Dichomitus squalens.
abstract: Two chromatographic forms of laccase c1 and c2 were purified approximately 225-fold from the extracellular culture fluid of ligninolytic cultures of Dichomitus squalens, using DEAE-Sepharose and Mono-Q fast protein liquid chromatography. Each homogeneous laccase (c1 and c2) has a molecular mass of approximately 66 kDa as determined by SDS-PAGE. Both forms are glycoproteins, and each contains four copper atoms per molecule of protein. The first 20 amino acids of the N-terminal sequences of these two laccases are identical and are similar to those of laccases from other lignin-degrading fungi. The electronic absorption spectra of these laccases exhibit bands at 610 and 330 nm, indicative of type I and type III copper. The EPR spectrum of laccase c1 exhibits bands indicative of type I and type II copper. Each laccase oxidizes a variety of phenolic substrates, has a pH optimum of 3.0 for the oxidation of 2,6-dimethoxyphenol, and is inhibited strongly by fluoride and azide.
authors.affiliation: Department of Biochemistry and Molecular Biology, Oregon Graduate Institute of Science and Technology, Portland 97291-1000, USA.
authors.forename: F H
authors.initials: FH
authors.lastname: Périé
authors.forename: G V
authors.initials: GV
authors.lastname: Reddy
authors.forename: N J
authors.initials: NJ
authors.lastname: Blackburn
authors.forename: M H
authors.initials: MH
authors.lastname: Gold
mesh_terms: D000595:Amino Acid Sequence; D001487:Basidiomycota / Q000187:drug effects / Q000201:enzymology*; D004578:Electron Spin Resonance Spectroscopy; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007527:Isoenzymes / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification*; D042845:Laccase; D008969:Molecular Sequence Data; D010088:Oxidoreductases / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification*; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D004791:Enzyme Inhibitors; D007527:Isoenzymes; D010088:Oxidoreductases; D042845:Laccase