Biomineralization of carbon dioxide by carbonic anhydrase

Increase in concentration of greenhouse gases is one of the major factors of climate change and among them contribution of carbon dioxide is more than other gases. Increase in temperature, warming of oceans, rise in sea level, shirking ice-sheaths, glacial retreat, ocean acidification are the consequences of increase in CO2 level. Human beings are also likely to be affected by various diseases at times. Globally much efforts have been made to reduce CO2 emission, but they are highly expensive and energy intensive. Carbonic anhydrase (CA) that can catalyze the reversible hydration and dehydration of CO2 and HCO3− respectively has arrived a better and ecofriendly enzymatic method for CO2 removal. Thus, one of the most efficient approaches is the use of CA as a biocatalyst in the biosequestration of carbon. For industrial application of CA in biomimetic carbon sequestration, it needs to possess two essential properties, viz., thermostability and alkali stability, that can be achieved by approaches such as protein engineering, whole cell biocatalysis and immobilization. Enzyme immobilization methods have opened a new path for industrial-scale applications by effective enzymatic recovery, reusability, and long-term operating stability. The various methods of immobilization with their merits and limitations along with ongoing research work in this field has been addressed here. The relevance of bioinformatics is being realized in the era of genomics, assisting in genome-wide identification, characterization of putative gene families of different enzymes for diverse industrial applications. This analysis for industrially important enzyme has been done by authors to improve the catalytic efficiency, thermostability and structural stability. This review also gives a structural overview of different classes of CA discovered till date, and their evolutionary relationships has been studied using multiple sequence alignment (MSA).