The protein encoded by the Nce103 gene of Saccharomyces cerevisiae, a beta-carbonic anhydrase ( CA, EC 188.8.131.52) designated as scCA, has been cloned, purified, characterized kinetically and investigated for its inhibition with a series of sulfonamides and one sulfamate. The enzyme showed high CO2 hydrase activity, with a k(cat) of 9.4 x 10(5) s (1), and k(cat)/K-M of 9.8 x 10(7) M (1) s (1). Simple benzenesulfonamides substituted in 2-, 4- and 3,4- positions of the benzene ring with amino, alkyl, halogeno and hydroxyalkyl moieties were weak scCA inhibitors with K(I)s in the range of 0.976-18.45 mu M. Better inhibition (K(I)s in the range of 154-654 nM) was observed for benzenesulfonamides incorporating aminoalkyl/carboxyalkyl moieties or halogenosulfanilamides; benzene-1,3-disulfonamides; simple heterocyclic sulfonamides and sulfanilyl-sulfonamides. The clinically used sulfonamides/ sulfamate ( acetazolamide, ethoxzolamide, methazolamide, dorzolamide, topiramate, celecoxib, etc.) generally showed effective scCA inhibitory activity, with K(I)s in the range of 82.6-133 nM. The best inhibitor (K-I of 15.1 nM) was 4-( 2-amino-pyrimidin-4-yl)-benzenesulfonamide. These inhibitors may be useful to better understand the physiological role of beta-CAs in yeast and some pathogenic fungi which encode orthologues of the yeast enzyme and eventually for designing novel antifungal therapies. (c) 2008 Elsevier Ltd. All rights reserved.