title: Inhibitory effects of divalent metal ions on liver microsomal 7-ethoxyresorufin O-deethylase (EROD) activity of leaping mullet.
abstract: The purpose of the present study was to elucidate in vitro effects of Hg(2+), Zn(2+), Ni(2+) and Cd(2+) on cytochrome P4501A1 (CYP1A1) dependent EROD activities in leaping mullet liver microsomes. Fish captured from the most polluted part of Izmir Bay, had highly elevated EROD activities, and induced CYP1A1 protein levels as determined by Western blotting. Although all of the metal ions caused inhibition of the initial velocity of the reaction, Hg(2+) and Cd(2+) exhibited much higher inhibitory effect at lower concentrations and they were evidently more potent inhibitors than others. The inhibitor concentration giving 50% inhibition (IC(50) values) of Zn(2+), Ni(2+), Cd(2+) and Hg(2+) of initial EROD activity were 107, 16, 1.3 and 0.15 micromolar, respectively. Glutathione (GSH) at 0.5 mM final concentration, completely reversed Ni(2+) and Cd(2+) inhibition of EROD activity indicating the protective action of GSH.
authors.affiliation: Department of Biological Sciences, Joint Graduate Program in Biochemistry, Middle East Technical University, 06531 Ankara, Turkey.
authors.forename: Azra
authors.initials: A
authors.lastname: Bozcaarmutlu
authors.forename: Emel
authors.initials: E
authors.lastname: Arinç
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002413:Cations, Divalent / Q000633:toxicity; D019363:Cytochrome P-450 CYP1A1 / Q000096:biosynthesis*; D004305:Dose-Response Relationship, Drug; D004790:Enzyme Induction / Q000187:drug effects; D005618:Fresh Water; D005978:Glutathione / Q000494:pharmacology*; D007928:Lethal Dose 50; D008099:Liver / Q000201:enzymology*; D019216:Metals, Heavy / Q000633:toxicity*; D008861:Microsomes / Q000201:enzymology*; D012044:Regression Analysis; D023701:Smegmamorpha / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D014421:Turkey
chemical_list: D002413:Cations, Divalent; D019216:Metals, Heavy; D019363:Cytochrome P-450 CYP1A1; D005978:Glutathione