Isolation, purification, and characterization of carbonic anhydrase from Azadirachta indica (neem) leaves and its CO2 sequestration efficiency

Carbonic anhydrase (CA) has been purified, immobilized, and characterized from a novel plant source Azadirachta indica (neem) leaves. The CA enzyme was purified to homogeneity to 19-fold. By SDS-PAGE the molecular mass of the purified CA was obtained to be 42.49 kDa. The pI value of the purified CA was found to be 4.95. Immobilization study of the purified CA was carried out with chitosan beads. The pH and temperature optima for free and immobilized enzyme were found to be 8.0, 30 °C and 9.0, 40 °C, respectively. From Lineweaver burk plot the km and Vmax values of the free and immobilized CA were found to be 0.89 mM, 0.118 μmol/min and 1.04 mM, 0.083 μmol/min, respectively. The storage stability of the free and immobilized CA was studied for 30 days where the immobilized CA was found to show better stability. The immobilized CA also showed satisfactory reusable capacity. Both free and immobilized neem leaves CA exhibited good CO2 sequestration capacity, forming CaCO3 formation in presence of CaCl2·2H2O under optimized conditions. The formed CaCO3 were further characterized by SEM, XRD, and FTIR.