“…CAs are ubiquitous metalloenzymes that catalyze the reversible hydration of carbon dioxide with the production of bicarbonate and protons. The CA superfamily includes seven distinct classes known as the α, β, γ, δ, ζ, η, and θ [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 ]. The α-, β-, δ-, η-, and perhaps θ-CAs use Zn(II) ions at the active site, the γ-CAs are probably Fe(II) enzymes (but they are also active with bound Zn(II) or Co(II) ions) [ 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ], and the ζ-class CAs are cambialistic enzymes, active both with Cd(II) or Zn(II) bound within the active site in order to perform the physiologic reaction catalysis [ 22 , 23 , 24 ].…”