title: Biochemical characterization of the native α-carbonic anhydrase purified from the mantle of the Mediterranean mussel, Mytilus galloprovincialis.
abstract: A α-carbonic anhydrase (CA, EC 4.2.1.1) has been purified and characterized biochemically from the mollusk Mytilus galloprovincialis. As in most mollusks, this α-CA is involved in the biomineralization processes leading to the precipitation of calcium carbonate in the mussel shell. The new enzyme had a molecular weight of 50 kDa, which is roughly two times higher than that of a monomeric α-class enzyme. Thus, Mytilus galloprovincialis α-CA is either a dimer, or similar to the Tridacna gigas CA described earlier, may have two different CA domains in its polypeptide chain. The Mytilus galloprovincialis α-CA sequence contained the three His residues acting as zinc ligands and the gate-keeper residues present in all α-CAs (Glu106-Thr199), but had a Lys in position 64 and not a His as proton shuttling residue, being thus similar to the human isoform hCA III. This probably explains the relatively low catalytic activity of Mytilus galloprovincialis α-CA, with the following kinetic parameters for the CO2hydration reaction: kcat= 4.1 × 105s-1and kcat/Kmof 3.6 × 107M-1× s-1. The enzyme activity was poorly inhibited by the sulfonamide acetazolamide, with a KIof 380 nM. This study is one of the few describing in detail the biochemical characterization of a molluskan CA and may be useful for understanding in detail the phylogeny of these enzymes, their role in biocalcification processes and their potential use in the biomimetic capture of the CO2.
authors.affiliation: a Istituto di Bioscienze e Biorisorse, CNR , Napoli , Italy.
authors.forename: Rosa
authors.initials: R
authors.lastname: Perfetto
authors.affiliation: a Istituto di Bioscienze e Biorisorse, CNR , Napoli , Italy.|b Dipartimento Neurofarba , Università degli Studi di Firenze, Sezione di Scienze Farmaceutiche, and Laboratorio di Chimica Bioinorganica, Polo Scientifico , Sesto Fiorentino , Florence , Italy.
authors.forename: Sonia
authors.initials: S
authors.lastname: Del Prete
authors.affiliation: b Dipartimento Neurofarba , Università degli Studi di Firenze, Sezione di Scienze Farmaceutiche, and Laboratorio di Chimica Bioinorganica, Polo Scientifico , Sesto Fiorentino , Florence , Italy.
authors.forename: Daniela
authors.initials: D
authors.lastname: Vullo
authors.affiliation: c Dipartimento di Biologia , Università degli Studi di Napoli, Federico II , Napoli , Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Sansone
authors.affiliation: d Dipartimento di Agraria , Università degli Studi di Napoli, Federico II , Portici (Napoli) , Italy.
authors.forename: Carmela
authors.initials: C
authors.lastname: Barone
authors.affiliation: a Istituto di Bioscienze e Biorisorse, CNR , Napoli , Italy.
authors.forename: Mosè
authors.initials: M
authors.lastname: Rossi
authors.affiliation: b Dipartimento Neurofarba , Università degli Studi di Firenze, Sezione di Scienze Farmaceutiche, and Laboratorio di Chimica Bioinorganica, Polo Scientifico , Sesto Fiorentino , Florence , Italy.
authors.forename: Claudiu T
authors.initials: CT
authors.lastname: Supuran
authors.affiliation: a Istituto di Bioscienze e Biorisorse, CNR , Napoli , Italy.
authors.forename: Clemente
authors.initials: C
authors.lastname: Capasso
mesh_terms: D000818:Animals; D002257:Carbonic Anhydrase Inhibitors / Q000494:pharmacology; D002256:Carbonic Anhydrases / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism*; D049878:Mytilus / Q000033:anatomy & histology / Q000201:enzymology*
chemical_list: D002257:Carbonic Anhydrase Inhibitors; D002256:Carbonic Anhydrases
keywords: Carbonic anhydrase; bivalve; hydratase activity; metalloenzymes; mussel; protonography; α-class enzyme