The inhibition kinetics of bovine and human erythrocyte carbonic anhydrase isozymes with some active cations

Abstract

In this study, the in vitro effects of some active cations on carbonic anhydrase (CA) isozymes were investigated. Bovine (BCA) and human (HCA-I and H CA-ll) isozymes were purified by affinity chromatography from bovine and human erythrocytes. In order to make the kinetic studies, esterase activities of CA isozymes were determined. By using AI{3+}, Mn{2+}, Sr{2+}, Hg{2+}, Ni{2+}, Ca{2+}, and Cd{2+}ions, K iconstants for CA isozymes were found by means of Linewear-Burk graphics. While A1{3+} showed competitive inhibition, the others displayed noncompetitive inhibition. In addition, the inhibitor concentrations halving the enzyme activity (I{50} values) were determined. The determined I{50} values for BCA, HCA-I and CA-ll were fit to the obtained Ki values.