Anion inhibition studies of a β-carbonic anhydrase from Clostridium perfringens

A beta-carbonic anhydrases (CAs, EC 4.2.1.1) was recently cloned, purified and characterized kinetically in the pathogen Clostridium perfringens. We report here the first inhibition study of this enzyme (CpeCA). CpeCA was poorly inhibited by iodide and bromide, and was inhibited with K(I)s in the range of 1-10 mM by a range of anions such as (thio) cyanate, azide, bicarbonate, nitrate, nitrite, hydrogensulfite, hydrogensulfide, stannate, tellurate, pyrophosphate, divanadate, tetraborate, peroxydisulfate, sulfate, iminodisulfonate and fluorosulfonate. Better inhibitory power, with K(I)s of 0.36-1.0 mM, was observed for cyanide, carbonate, selenate, selenocyanide, trithiocarbonate and diethyldithiocarbamate, whereas the best CpeCA inhibitors were sulfamate, sulfamide, phenylboronic acid and phenylarsonic acid, which had K(I)s in the range of 7-75 mu M. This study thus provides the basis for developing better clostridial enzyme inhibitors with potential as antiinfectives with a new mechanism of action. (C) 2013 Elsevier Ltd. All rights reserved.