Figure 1.

Biological assembly of the alpha-carbonic anhydrase (α-CA) from Thermovibrio ammonificans (TaCA, PDB ID: 4C3T). (A) illustrates the equations for CO₂ hydration and dehydration (1 and 2) as well as metal carbonation (3), while (B) shows the tetrameric structure of TaCA. (C) shows the disulfide core formed by four Cys residues in the tetramerization interface. The catalytic cavity is enlarged in (D), with CO₂ binding pocket residues colored red, proton transfer residues in blue and Zn²⁺ coordinating His residues colored green.