Anhydrases carboniques érythrocytaires bovines : étude comparée des activités anhydrasiques et estérasiques des différentes formes

Abstract

Comparative study of esterase activities (p- and o-nitrophenylacetate) allowed to characterize three groups of bovine erythrocyte carbonic anhydrases:--the first one includes CI, CII (isozyme of CI) and CIr ("artificial" product of CI).--the second one includes native CIv1 and "artificial" CIv1, first conformational variants of CI,--finally CIv2, second "artificial" conformational variant of CI. Possible modifications of the enzyme site between the first and the other enzyme groups are discussed. Except CIv2 of lower activity, all the products have identical carbonic anhydrase activity. The catalytic constants Km ap and kcat ap for hydrolysis of p-nitrophenylacetate have been determined for all enzymes; this study confirms the lower activity of CIv2.