title: Paraoxon, 4-nitrophenyl phosphate and acetate are substrates of α- but not of β-, γ- and ζ-carbonic anhydrases.
abstract: Carbonic anhydrases (CAs, EC 4.2.1.1) belonging to α-, β-, γ- and ζ-classes and from various organisms, ranging from the bacteria, archaea to eukarya domains, were investigated for their esterase/phosphatase activity with 4-nitrophenyl acetate, 4-nitrophenyl phosphate and paraoxon as substrates. Only α-CAs showed esterase/phosphatase activity, whereas enzymes belonging to the β-, γ- and ζ-classes were completely devoid of such activity. Paraoxon, the metabolite of the organophosphorus insecticide parathione, was a much better substrate for several human/murine α-CA isoforms (CA I, II and XIII), with k(cat)/K(M) in the range of 2681.6-4474.9M(-1)s(-1), compared to 4-nitrophenyl phosphate (k(cat)/K(M) of 14.9-1374.4M(-1)s(-1)).
authors.affiliation: Università degli Studi di Firenze, Polo Scientifico, Laboratorio di Chimica Bioinorganica, Rm. 188, Via della Lastruccia 3, 50019 Sesto Fiorentino (Florence), Italy.
authors.forename: Alessio
authors.initials: A
authors.lastname: Innocenti
authors.forename: Claudiu T
authors.initials: CT
authors.lastname: Supuran
mesh_terms: D000818:Animals; D002245:Carbon Dioxide / Q000378:metabolism; D002257:Carbonic Anhydrase Inhibitors / Q000737:chemistry; D002256:Carbonic Anhydrases / Q000378:metabolism*; D002384:Catalysis; D006801:Humans; D007306:Insecticides / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism; D007700:Kinetics; D051379:Mice; D009596:Nitrophenols / Q000378:metabolism*; D009943:Organophosphorus Compounds / Q000378:metabolism*; D010261:Paraoxon / Q000378:metabolism*; D013379:Substrate Specificity
chemical_list: D002257:Carbonic Anhydrase Inhibitors; D007306:Insecticides; D007527:Isoenzymes; D009596:Nitrophenols; D009943:Organophosphorus Compounds; D002245:Carbon Dioxide; C008644:nitrophenylphosphate; C008642:4-nitrophenyl acetate; D002256:Carbonic Anhydrases; D010261:Paraoxon