title: Purification of a new manganese peroxidase of the white-rot fungus Irpex lacteus, and degradation of polycyclic aromatic hydrocarbons by the enzyme.
abstract: The white-rot fungus Irpex lacteus has been reported to be an efficient degrader of polycyclic aromatic hydrocarbons, polychlorinated biphenyls and pentachlorophenol. The fungus produces ligninolytic enzymes laccase, lignin peroxidase and manganese peroxidase (MnP), the latter being the major one produced. MnP was purified using anion exchange and size exclusion chromatography. SDS-PAGE showed the purified MnP to be a monomeric protein of 37 kDa (37.5 kDa using MALDI-TOF) with an isoelectric point at 3.55. The pH optimum was relatively broad, from 4.0 to 7.0 with a peak at pH 5.5. Kinetic constants K(m) were 8 microM for H(2)O(2) and 12 or 31 microM for Mn(2+) depending on the substrate. The enzyme did not perform oxidation in the absence of H(2)O(2) or Mn(2+). MnP was active at 5-70 degrees C with an optimum between 50-60 degrees C. At temperatures above 65 degrees C the enzyme rapidly lost activity. Degradation of four representatives of PAHs (phenanthrene, anthracene, fluoranthene, and pyrene) was tested and the enzyme showed the ability to degrade them in vitro. Major degradation products of anthracene were identified. The results confirm the role of MnP in PAH degradation by I. lacteus, including cleavage of the aromatic ring.
authors.affiliation: Institute of Microbiology AS CR, Prague, Czech Republic.
authors.forename: Petra
authors.initials: P
authors.lastname: Baborová
authors.forename: Monika
authors.initials: M
authors.lastname: Möder
authors.forename: Petr
authors.initials: P
authors.lastname: Baldrian
authors.forename: Kamila
authors.initials: K
authors.lastname: Cajthamlová
authors.forename: Tomás
authors.initials: T
authors.lastname: Cajthaml
mesh_terms: D001487:Basidiomycota / Q000201:enzymology*; D001673:Biodegradation, Environmental; D002852:Chromatography, Ion Exchange; D004785:Environmental Pollutants / Q000378:metabolism*; D010416:Pentachlorophenol / Q000378:metabolism; D010544:Peroxidases / Q000302:isolation & purification / Q000378:metabolism*; D011078:Polychlorinated Biphenyls / Q000378:metabolism; D011084:Polycyclic Aromatic Hydrocarbons / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D004785:Environmental Pollutants; D011084:Polycyclic Aromatic Hydrocarbons; D010416:Pentachlorophenol; D011078:Polychlorinated Biphenyls; D010544:Peroxidases; C051129:manganese peroxidase