Immobilization of Carbonic Anhydrase on Chitosan Stabilized Iron Nanoparticles for the Carbonation Reaction

Abstract

Carbonic anhydrase (CA) has been immobilized on chitosan stabilized iron nanoparticles (CSIN) for the biomimetic carbonation reaction. CSIN was characterized using scanning electron microscope, energy dispersive X-ray, X-ray diffraction spectroscopy, and Fourier transform infrared analysis. The effect of various parameters such as pH, temperature and storage stability, on immobilized CA was investigated using a p-NPA assay. Kinetic parameters of immobilized and free CA (K m and V max values) were also evaluated. The K m and V max for immobilized CA was 1.727 mM and 1.189 μmol min−1 ml−1, respectively, whereas for free enzyme the K m and V max was 1.594 mM and 1.307 μmol min−1 ml−1, respectively. It was observed that the immobilized enzyme had longer storage stability and retained 50 % of its initial activity upto 30 days at room temperature. CA immobilized on CSIN has been used for hydration of CO2, and the results were validated by using a gas chromatographic method. Proof of concept has been established for the biomimetic carbonation reaction. Immobilized CA show reasonably good CO2 sequestration capacity of 21.55 mg of CaCO3/mg of CA as compared to CO2 sequestration capacity of 34.92 mg of CaCO3/mg of CA for free CA respectively, under a limiting concentration of CO2 (14.5 mg of CO2/10 ml).