Delta carbonic anhydrases are one of the at least five independently evolved families of carbonic anhydrases. Their activities, low CO2-induction, and localizations have been well studied in diatoms [1-2]. The catalytic mechanism of delta CAs is currently unknown. Proteins of this family are also common in bacteria, but due to more distant relationship (identities less than 30% to the diatom delta CAs) and to the lack of experimental data the carbonic anhydrase activity is only putative in prokaryotic delta CAs.

1: Cloning, Expression and Characterization of the delta-carbonic Anhydrase of Thalassiosira weissflogii (Bacillariophyceae). Lee RB, Smith JA, Rickaby RE; J Phycol. 2013;49:170-177. PMID:27008398

2: Localization of putative carbonic anhydrases in the marine diatom, Thalassiosira pseudonana. Samukawa M, Shen C, Hopkinson BM, Matsuda Y; Photosynth Res. 2014;121:235-249. PMID:24414291