A new carbonic anhydrase identified in the Gram-negative bacterium (Chromohalobacter sp.) and the interaction of anions with the enzyme.

In this study, the characterization and inhibition characteristic of α-class carbonic anhydrase from Chromohalobacter (ChCA) was documented for the first time. The carbonic anhydrase enzyme had 47.77% yield and 54.45-fold purity. The specific activity of the enzyme was determined as 318.52 U/mg proteins. Alternative substrate (4-nitrophenyl trifluoroacetate, 4-nitrophenyl phosphate, 4-nitrophenyl sulphate and 4-nitrophenyl acetate) were tested for the enzyme. KM and Vmax values for 4-nitrophenyl acetate were 4.57 mM and 4.29 EU/mL and for 4-nitrophenyl trifluoroacetate were 2.39 mM and 2.41 EU/mL. The anions, Cl-, NO2-, NO3-, Br-, ClO3-, ClO4-, I-, CO32- and SO42-, inhibited the ChCA hydratase activity. Among nine anions, the strongest inhibitor activities were obtained with micro molar concentrations of NO2-, NO3-, Br-, I-, CO32- (KI values of 160-255 µM). Other four anions tested (Cl-, ClO3-, ClO4- and SO42-) showed moderate inhibitory activities (KI values of 680-813.5 µM). The results obtained demonstrate that the anions we tested inhibit the Chromohalobacter CA (ChCA) enzyme as in other α-CAs in mammals; however, the susceptibility of ChCA resulted from anions differed significantly from that of other organism CAs.