An inhibition study of the cytosolic carbonic anhydrase (CA, EC 4.2.1.1) isozyme VII (hCA VII) with anions has been conducted. Cyanate, cyanide, and hydrogensulfite were weak hCA VII inhibitors (K(I)s in the range of 7.3-15.2 mM). Cl- and HCO3- showed good inhibitory activity against hCA VII (K(I)s of 0.16-1.84 mM), suggesting that this enzyme is not involved in metabolons with anion exchangers or sodium bicarbonate cotransporters. The best inhibitors were sulfamate, sulfamide, phenylboronic, and phenylarsonic acid (K(I)s of 6.8-12.5 microM).