title: Cloning, characterization and anion inhibition studies of a new γ-carbonic anhydrase from the Antarctic bacterium Pseudoalteromonas haloplanktis.
abstract: A new γ-class carbonic anhydrase (CA, EC 4.2.1.1) was cloned, purified and characterized from the Antarctic bacterium Pseudoalteromonas haloplanktis, PhaCAγ. The enzyme has a medium-low catalytic activity for the physiologic reaction of CO2 hydration to bicarbonate and protons, with a kcat of 1.4×10(5)s(-1) and a kcat/Km of 1.9×10(6)M(-1)s(-1). An anion inhibition study of PhaCAγ with inorganic anions and small molecule inhibitors is also reported. Many anions present in sea water, such as chloride, fluoride, sulfate, iodide, but also others such as azide, perchlorate and tetrafluoroborate did not inhibit this enzyme. Pseudohalides such as cyanate, thiocyanate, cyanide, selenocyanide, and also bicarbonate, nitrate, nitrite and many complex inorganic anions showed inhibition in the millimolar range (KI in the range of 1.7-9.3mM). The best PhaCAγ inhibitors detected in this study were diethyldithiocarbamate (KI of 0.96 mM) as well as sulfamide, sulfamate, phenylboronic acid and phenylarsonic acid (KI in the range of 82-91 μM). Since γ-CAs are poorly understood at this moment, being present in carboxysomes and thus involved in photosynthesis, this study may be relevant for a better understanding of these processes in Antarctic bacteria/cyanobacteria.
authors.affiliation: Istituto di Bioscienze e Biorisorse, CNR, Via Pietro Castellino 81, Napoli, Italy.
authors.forename: Viviana
authors.initials: V
authors.lastname: De Luca
authors.affiliation: Università degli Studi di Firenze, Dipartimento Di Chimica, Laboratorio di Chimica Bioinorganica, Polo Scientifico, Via della Lastruccia 3, 50019 Sesto Fiorentino, Florence, Italy.
authors.forename: Daniela
authors.initials: D
authors.lastname: Vullo
authors.affiliation: Istituto di Bioscienze e Biorisorse, CNR, Via Pietro Castellino 81, Napoli, Italy; Università degli Studi di Firenze, Dipartimento Di Chimica, Laboratorio di Chimica Bioinorganica, Polo Scientifico, Via della Lastruccia 3, 50019 Sesto Fiorentino, Florence, Italy.
authors.forename: Sonia
authors.initials: S
authors.lastname: Del Prete
authors.affiliation: Istituto di Bioscienze e Biorisorse, CNR, Via Pietro Castellino 81, Napoli, Italy.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Carginale
authors.affiliation: Università degli Studi di Firenze, Dipartimento Di Chimica, Laboratorio di Chimica Bioinorganica, Polo Scientifico, Via della Lastruccia 3, 50019 Sesto Fiorentino, Florence, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Scozzafava
authors.affiliation: Department of Chemistry, College of Science, King Saud University, PO Box 2455, Riyadh 11451, Saudi Arabia.
authors.forename: Sameh M
authors.initials: SM
authors.lastname: Osman
authors.affiliation: Department of Chemistry, College of Science, King Saud University, PO Box 2455, Riyadh 11451, Saudi Arabia.
authors.forename: Zeid
authors.initials: Z
authors.lastname: AlOthman
authors.affiliation: Università degli Studi di Firenze, Dipartimento Di Chimica, Laboratorio di Chimica Bioinorganica, Polo Scientifico, Via della Lastruccia 3, 50019 Sesto Fiorentino, Florence, Italy; Università degli Studi di Firenze, Dipartimento Neurofarba, Sezione di Scienze Farmaceutiche, Polo Scientifico, Via U. Schiff 6, 50019 Sesto Fiorentino, Florence, Italy. Electronic address: claudiu.supuran@unifi.it.
authors.forename: Claudiu T
authors.initials: CT
authors.lastname: Supuran
authors.affiliation: Istituto di Bioscienze e Biorisorse, CNR, Via Pietro Castellino 81, Napoli, Italy. Electronic address: clemente.capasso@ibbr.cnr.it.
authors.forename: Clemente
authors.initials: C
authors.lastname: Capasso
mesh_terms: D000595:Amino Acid Sequence; D000838:Anions / Q000737:chemistry; D002257:Carbonic Anhydrase Inhibitors / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism; D002256:Carbonic Anhydrases / Q000145:classification / Q000235:genetics / Q000378:metabolism; D003001:Cloning, Molecular; D007700:Kinetics; D008969:Molecular Sequence Data; D010802:Phylogeny; D011485:Protein Binding; D031161:Pseudoalteromonas / Q000201:enzymology*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification; D016415:Sequence Alignment
chemical_list: D000838:Anions; D002257:Carbonic Anhydrase Inhibitors; D011994:Recombinant Proteins; D002256:Carbonic Anhydrases
keywords: Anions; Antarctic carbonic anhydrase; Carbonic anhydrase; Cold adaptation; Cold-enzymes; Hydratase activity; Inhibitors; Metalloenzymes; Psychrophiles