Immobilization of carbonic anhydrase on mesoporous aluminosilicate for carbonation reaction

Mesoporous aluminosilicates synthesized using a template of Pluronic F127 with high surface area and pore diameter appears to be tailor made for enzyme adsorption. Carbonic anhydrase (CA) with diameter of 35 Å has been immobilized in these crystalline, ordered mesoporous materials and tested for mechanistic and kinetic aspects using p-NPA assay. Km, Vmax and Kcat of the CAImAlK was observed to be 0.158 mM, 2.307 μmol/min/ml and 1.9 s−1, respectively compared to Km, Vmax and Kcat of 0.876 mM, 0.936 μmol/min/ml and 2.3 s−1, respectively for free CA. Storage stability test was conducted up to 25 days and it was observed that the HLP at 25 °C improved by a factor of 1.6 for CAImAlK (600 h) compared to 360 h for free CA. Proof of concept has been established for carbonation reaction. The CO2 sequestration capacity in terms of conversion of CO2 to calcium carbonate was quantified by gas chromatography (GC). The CO2 sequestration capacity of CAImAlK was determined to be 16.14 mg of CaCO3/mg of CA compared to 33.08 mg of CaCO3/mg of CA for free CA.

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► AlKIT-5 with high surface area appears promising for the CA immobilization.
► Km and Vmax values for CAImAlK were found to be 0.158 mM and 2.307 μmol/min/ml.
► The HLP at 25 °C improved by a factor of 1.6 for CAImAlK.
► Proof of concept has been established for carbonation reaction.
► The CaCO3 was characterized by XRD and SEM analysis confirms calcite nature of CaCO3.