Inhibition studies with simple and complex (in)organic anions of the γ-carbonic anhydrase from MscCAγ.

The γ-carbonic anhydrase (CA, EC 4.2.1.1) from the pathogenic bacterium, (MscCAγ) was recently cloned and purified by our groups. Here we investigated inhibition of this enzyme with (in)organic simple and complex anions, in the search of inhibitors with potential applications. The most effective inhibitors (Ks in the micromolar range) were peroxydisulfate and trithiocarbonate, whereas submillimolar inhibition was observed with -diethyldithiocarbamate and phenylboronic acid (Ks of 0.5-0.9 mM). Thiocyanate, hydrogensulfide, bisulphite, stannate, divanadate, tetraborate, perrhenate, perruthenate, hexafluorophosphate, triflate and iminodisulfonate showed Ks of 1.0-13.7 mM. Cyanate, cyanide, azide, carbonate, nitrate, tellurate, selenocyanide, tetrafluoroborate, sulfamide, sulphamic acid and phenylarsonic acid were weaker inhibitors, with Ks in the range of 25.2-95.5 mM, whereas halides, bicarbonate, nitrite, sulphate, perchlorate and fluorosulfonate did not show inhibitory action up until 100 mM concentrations in the assay system. Finding more effective MscCAγ inhibitors may be helpful to fight drug resistance to antibiotics.