Carbonic anhydrase activators: Activation of isozyme XIII with amino acids and amines

The first activation study of isoform XIII of carbonic anhydrase (CA, EC 4.2.1.1) is reported. A series of amino acids and amines incorporating protonatable moieties of the primary/heterocyclic amine type were included in the study. As for CA I and 11, CA XIII activators enhance k(cat) and show no effect on K-M, for the physiologic reaction catalyzed by this isoform. Excellent CA XIII activating properties were shown by D-amino acids (His, Phe, DOPA, and Trp), serotonin, and 4-(2-aminoethyl)-morpholine, whereas the corresponding L-amino acids, dopamine, histamine, and 1-(2-aminoethyl)-piperazine, were weaker activators. (c) 2006 Elsevier Ltd. All rights reserved.