title: Evidence for cytochrome P-450 and P-450-mediated benzo(a)pyrene hydroxylation in the white rot fungus Phanerochaete chrysosporium.
abstract: The presence of cytochrome P-450 and P-450-mediated benzo(a)pyrene hydroxylase activity in both microsomal and soluble fractions of the white rot fungus Phanerochaete chrysosporium was shown. The reduced carbon monoxide difference spectrum showed maxima at 448-450 and 452-454 nm for microsomal and cytosolic fractions, respectively. Both P-450 fractions produced a Type I substrate binding spectrum on addition of benzo(a)pyrene. Activity for benzo(a)pyrene hydroxylation was NADPH dependent and inhibited by carbon monoxide. Km values for activity showed a difference between the cellular fractions with a Km of 89 microM for microsomal P-450 and 400 microM for cytosolic P-450. The Vmax values observed were 0.83 nmol min-1 (nmol microsomal P-450)-1 and 0.4 nmol min-1 (nmol cytosolic P-450)-1. The results indicate that P-450-mediated benzo(a)pyrene hydroxylase activity could play a role in xenobiotic transformation by this fungus beside the known ligninolytic exocellular enzymes.
authors.affiliation: MIGAL Technology Centre, Kiryat Shmona, Israel.
authors.forename: S
authors.initials: S
authors.lastname: Masaphy
authors.forename: D
authors.initials: D
authors.lastname: Levanon
authors.forename: Y
authors.initials: Y
authors.lastname: Henis
authors.forename: K
authors.initials: K
authors.lastname: Venkateswarlu
authors.forename: S L
authors.initials: SL
authors.lastname: Kelly
mesh_terms: D001487:Basidiomycota / Q000201:enzymology* / Q000378:metabolism; D001564:Benzo(a)pyrene / Q000378:metabolism*; D001673:Biodegradation, Environmental; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D006900:Hydroxylation; D008031:Lignin / Q000378:metabolism; D008861:Microsomes / Q000201:enzymology / Q000378:metabolism
chemical_list: D001564:Benzo(a)pyrene; D008031:Lignin; D003577:Cytochrome P-450 Enzyme System