Carbonic anhydrase in relation to higher plants

The review incorporates recent information on carbonic anhydrase (CA, EC: 4.2.1.1) pertaining to types, homology, regulation, purification, in vitro stability, and biological functions with special reference to higher plants. CA, a ubiquitous enzyme in prokaryotes and higher organisms represented by four distinct families, is involved in diverse biological processes, including pH regulation, CO₂ transfer, ion exchange, respiration, and photosynthetic CO₂ fixation. CA from higher plants traces its origin with prokaryotes and exhibits compartmentalization among their organs, tissues, and cellular organelles commensurate with specific functions. In leaves, CA represents 1–20 % of total soluble protein and abundance next only to ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCO) in chloroplast, facilitating CO₂ supply to phosphoenol pyruvate carboxylase in C₄ and CAM plants and RuBPCO in C₃ plants. It confers special significance to CA as an efficient biochemical marker for carbon sequestration and environmental amelioration in the current global warming scenario linked with elevated CO₂ concentrations.