Immobilized Carbonic Anhydrase for the Biomimetic Carbonation Reaction

Abstract

Carbonic anhydrase (CA) has been immobilized on surfactant-modified silylated chitosan (SMSC) for the carbonation reaction. CA immobilized on SMSC was characterized using a scanning electron microscope, energy-dispersive X-ray and 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-nitrophenyl acetate (p-NPA) assay. The optimum pH and temperature were determined to be 7 and 35 °C, respectively. Kinetic parameters of immobilized and free CA (K m and V max values) were also evaluated. For immobilized CA, the K m value was 4.547 mM and the V max value was 1.018 mmol min -1 mg -1 , whereas for the free CA, the K m value was 1.211 mM and the V max value was 1.125 mmol min -1 mg -1 . It was observed that immobilized CA had longer storage stability and retained 50% of its initial activity up to 30 days. Proof of concept has been established for the biomimetic carbonation reaction. The CO 2 sequestration capacity in terms of conversion of CO 2 to carbonate was quantified by gas chromatography (GC). It was 10.73 and 14.92 mg of CaCO 3 /mg of CA for immobilized and free CA, respectively, under a limiting concentration of CO 2 (14.5 mg of CO 2 /10 mL).

Carbon sequestration via carbonic anhydrase facilitated magnesium carbonate precipitation

“…Numerous studies have investigated immobilizing CA onto a solid medium in order to increase its lifespan, particularly by minimizing exposure to denaturing conditions that may exist in an industrial carbon sequestration scenario (Cheng et al, 2008;Ozdemir, 2009;Sharma et al, 2011;Vinoba et al, 2012Vinoba et al, , 2011aWanjari et al, 2012;Yadav et al, 2011Yadav et al, , 2010. With particular relevance to this study, BCA immobilized within polyurethane foam preserved 100% activity over 45 days when stored in Tris buffer at ambient conditions in comparison to free BCA that lost its activity over the same period at 4 • C (Ozdemir, 2009).…”

The use of carbonic anhydrase to accelerate carbon dioxide capture processes

“…The immobilization of an enzyme to a solid substrate is a focal point for research because it aids the reuse of the enzyme and lengthens its lifespan . Immobilization has also been shown to improve the thermostability of various types of enzymes . In addition, with the immobilization of the enzymes within the absorption stage of the process, there is no need to expose them to the harsher temperature conditions within the stripper, which also helps to prolong their operational lifespan.…”

“…There have been reports of CA enzymes being immobilized onto activated carbon particles, polyurethane foams, silica nanoparticles, silica beads, chitosan, chitosan and silica coated magnetic particles and gold nanoparticles functionalized with silica . A wide array of methods have been used for immobilising CA onto the abovementioned surfaces, including the use of hydrogels, covalent bonding through reaction with aldehydes or with cyanogen bromide and triethylamine, cross‐linked aggregation, physical adsorption, and layer‐by‐layer (LbL) electrostatic adsorption .…”

Preparation of titania based biocatalytic nanoparticles and membranes for CO2conversion

“…The size, surface architecture, surface chemistry can have a significant effect on the immobilized enzyme performance. So far, various supports have been applied for CA immobilization including nanoparticles, chitosan, polyurethane foam and hydrogel [12][13][14][15][16][17] . Among different support, enzyme immobilization on nanoparticles has aroused increasing attention due to their larger surface area and better mobility.…”