title: Tributyltin (TBT) inhibition of oligomycin-sensitive Mg-ATPase activity in mussel mitochondria.
abstract: Tributyltin (TBT), one of the most toxic lipophilic aquatic pollutants, can be efficiently incorporated from sea water and sediments by filter-feeding molluscs. As far as we are aware TBT effects on the mitochondrial oligomycin-sensitive Mg-ATPase, the enzymatic core of energy production and a known target of TBT toxicity in mammals, have not been yet investigated in molluscs; thus the hydrolytic capability of the mitochondrial complex in the presence of micromolar concentrations of TBT was assayed in the mussel Mytilus galloprovincialis. Gill and mantle ATPase activities were progressively depressed by increasing TBT doses up to a maximal inhibition (82% in the gills and 74% in the mantle) at 0.62 microM TBT. Non-cooperative inhibition kinetics (n(H) approximately -1) and a non-competitive mechanism with respect to ATP substrate were pointed out. The mitochondrial Mg-ATPase susceptivity to TBT in the marine mussel was consistent with the formation of a TBT-Mg-ATPase complex, apparently more stable in the gills than in the mantle. The complex shape of the dose-response curve and the partial release of Mg-ATPase inhibition within the 0.6-34.4 microM TBT range suggest multiple interactions of TBT with the enzyme complex putatively related to its molecular mechanism of toxicity.
authors.affiliation: Department of Biochemistry G. Moruzzi, Section of Veterinary Biochemistry, University of Bologna, Via Tolara di Sopra, 50 - 40064 Ozzano Emilia (BO), Italy. alessandr.pagliarani@unibo.it <alessandr.pagliarani@unibo.it>
authors.forename: Alessandra
authors.initials: A
authors.lastname: Pagliarani
authors.forename: Patrizia
authors.initials: P
authors.lastname: Bandiera
authors.forename: Vittoria
authors.initials: V
authors.lastname: Ventrella
authors.forename: Fabiana
authors.initials: F
authors.lastname: Trombetti
authors.forename: Maurizio
authors.initials: M
authors.lastname: Pirini
authors.forename: Salvatore
authors.initials: S
authors.lastname: Nesci
authors.forename: Anna Rosa
authors.initials: AR
authors.lastname: Borgatti
mesh_terms: D000818:Animals; D017301:Ca(2+) Mg(2+)-ATPase / Q000187:drug effects* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005880:Gills / Q000187:drug effects / Q000201:enzymology; D066298:In Vitro Techniques; D008928:Mitochondria / Q000187:drug effects* / Q000201:enzymology; D049878:Mytilus / Q000201:enzymology; D009840:Oligomycins / Q000494:pharmacology; D014220:Trialkyltin Compounds / Q000008:administration & dosage / Q000633:toxicity*; D014874:Water Pollutants, Chemical / Q000008:administration & dosage / Q000633:toxicity*
chemical_list: D009840:Oligomycins; D014220:Trialkyltin Compounds; D014874:Water Pollutants, Chemical; C011559:tributyltin; D017301:Ca(2+) Mg(2+)-ATPase