Cadmium Carbonic Anhydrase
Cadmium: Cadmium is a metallic element with the oxidation state of +2, occurring rarely in metalloproteins, except some carbonic anhydrases. It is currently considered highly toxic, but in Cd-CAs, this metal ion has a catalytic role.
Carbonic anhydrase: Superfamily of metalloenzymes catalyzing CO2 hydration to bicarbonate and protons. Ubiquitous in all life kingdoms.
Biological implications: Cd-CAs are involved in CO2 fixations and photosynthesis in many diatoms.
Carbonic Anhydrase Families
The carbonic anhydrases (CAs, EC 220.127.116.11.) are a superfamily of metalloenzyme which evolved independently several times, with five genetically distinct enzyme classes known to date: the α-, β-, γ-, δ-, and ζ-CAs (Supuran 2008). The α-, β-, and δ-CAs use Zn(II) ions at the active site (Supuran 2008, 2010); the γ-CAs are probably Fe(II) enzymes (but they are active also with bound Zn(II) or Co(II) ions) (Ferry 2010), whereas the...