title: Carbonic anhydrase inhibitors: purification and inhibition studies of pigeon (Columba livia var. domestica) red blood cell carbonic anhydrase with sulfonamides.
abstract: A carbonic anhydrase (CA, EC 4.2.1.1) from red blood cells of pigeons (Columba livia var. domestica), clCA, was purified to homogeneity. Its kinetic parameters for the CO(2) hydration reaction were measured. With a k(cat)/K(m) of 1.1 × 10(8) M(-1) s(-1), and a k(cat) of 1.3 × 10(6) s(-1), clCA has a high activity, similar to that of the human isoform hCA II. A group of 25 aromatic/heterocyclic sulfonamides incorporating the sulfanilamide, homosulfanilamide, benzene-1,3-disulfonamide, and acetazolamide scaffolds showed variable inhibitory activity against the pigeon enzyme, with K(I)s in the range of 1.9-3460 nM. Red blood cells of pigeons, like those of ostriches, contain thus just one CA isoform, unlike the blood of mammals, which normally contain two isoforms, one of low (CA I-like) and one of very high activity (CA II-like). However, from the sulfonamide inhibition viewpoint, the pigeon enzyme was more similar to hCA II than to the ostrich enzyme.
authors.affiliation: Dipartimento di Chimica, Laboratorio di Chimica Bioinorganica, Polo Scientifico, Università degli Studi di Firenze, Sesto Fiorentino, Firenz, Italy.
authors.forename: Ozen
authors.initials: O
authors.lastname: Ozensoy
authors.forename: Mikail
authors.initials: M
authors.lastname: Arslan
authors.forename: Claudiu T
authors.initials: CT
authors.lastname: Supuran
mesh_terms: D000818:Animals; D001717:Birds; D002257:Carbonic Anhydrase Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D002256:Carbonic Anhydrases / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D004912:Erythrocytes / Q000201:enzymology; D015394:Molecular Structure; D020033:Protein Isoforms; D013449:Sulfonamides / Q000737:chemistry* / Q000494:pharmacology*
chemical_list: D002257:Carbonic Anhydrase Inhibitors; D020033:Protein Isoforms; D013449:Sulfonamides; D002256:Carbonic Anhydrases