Carbonic anhydrase example

The carbonic anhydrases (CAs, EC 4.2.1.1) are ubiquitous metalloenzymes, present in prokaryotes and eukaryotes, being encoded by three distinct, evolutionarily unrelated gene families: the α-CAs (present in vertebrates, bacteria, algae, and cytoplasm of green plants), the Β-CAs (predominantly in bacteria, algae, and chloroplasts of both mono- as well as dicotyledons), and the γ-CAs (mainly in archaea and some bacteria), respectively.^1-4 In higher vertebrates including humans, 14 different a- CA isozymes or CA-related proteins (CARP) were described, with very different subcellular localization and tissue distribution.^2-4 Basically, there are several cytosolic forms (CA I-III, CA VII), four membrane-bound isozymes (CA IV, CA IX, CA XII, and CA XIV), one mitochondrial form (CA V), as well as a secreted CA isozyme (CA VI), together with three acatalytic forms (isozymes CARP VIII, X, and XI).^2-4.