title: Restoring catalytic activity to the human carbonic anhydrase (CA) related proteins VIII, X and XI affords isoforms with high catalytic efficiency and susceptibility to anion inhibition.
abstract: Mutation of amino acid residues 94, 96 and 119 to histidine(s) in the human carbonic anhydrase (CA, EC 4.2.1.1) related proteins CARP VIII, X and XI restored the zinc binding and catalytic activity for the hydration of CO(2) to bicarbonate. CA VIII, X and XI thus obtained showed high catalytic activity (67.3-92.0% of the activity of hCA II and much higher compared to hCA I) and were inhibited in the milli-micromolar range by inorganic anions, sulfamide, sulfamic acid, phenylboronic acid and phenylarsonic acid. Among the three new isoforms, hCA X was the most efficient enzyme and also showed the highest affinity for anion inhibitors (K(I)s of 3.6-68 μM for phenylboronic acid, sufamic acid, sulfamide, cyanide and azide). hCA VIII was poorly inhibited by halides, cyanate, nitrate and sulfate (K(I)s of 38.4-65.4 mM), whereas CA XI had a behavior intermediate between that of hCA VIII and X, both regarding the catalytic activity and sensitivity to anion inhibitors.
authors.affiliation: Department of Gastroenterology and Hepatology, Kochi Medical School, Nankoku, Kochi 783-8505, Japan.
authors.forename: Isao
authors.initials: I
authors.lastname: Nishimori
authors.forename: Daniela
authors.initials: D
authors.lastname: Vullo
authors.forename: Tomoko
authors.initials: T
authors.lastname: Minakuchi
authors.forename: Andrea
authors.initials: A
authors.lastname: Scozzafava
authors.forename: Clemente
authors.initials: C
authors.lastname: Capasso
authors.forename: Claudiu T
authors.initials: CT
authors.lastname: Supuran
mesh_terms: D000595:Amino Acid Sequence; D000838:Anions / Q000737:chemistry*; D055162:Biocatalysis; D014408:Biomarkers, Tumor / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002257:Carbonic Anhydrase Inhibitors / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D002256:Carbonic Anhydrases; D047908:Intracellular Signaling Peptides and Proteins
chemical_list: D000838:Anions; D014408:Biomarkers, Tumor; D002257:Carbonic Anhydrase Inhibitors; D009419:Nerve Tissue Proteins; C512815:CA10 protein, human; C512817:CA11 protein, human; C512818:CA8 protein, human; D002256:Carbonic Anhydrases; D047908:Intracellular Signaling Peptides and Proteins