Human Carbonic Anhydrases II. SOME PHYSlCOCHEMICAL PROPERTIES OF NATIVE ISOZYMES AND OF SIMILAR ISOZYMES

Detailed studies of a relatively large number of human erythrocyte carbonic anhydrases of different electrophoretic mobilities have shown that individually each is very similar to one of the major isozymes, either B or C. The enzymatic activities, the zinc, nitrogen, and amino acid contents, and the molecular weights of members of a given type are similar. Some differences in the tryptic peptides and in the amide contents of the more acidic carbonic anhydrase B type isozymes are seen. Incubation of either carbonic anhydrase B or carbonic anhydrase C at relatively high pH leads to the formation of more acidic isozymes of the same type. These forms generated in vitro appear to be identical with the same type carbonic anhydrases of similar electrophoretic properties isolated from erythrocytes.