Immobilization of carbonic anhydrase and an artificial Zn(II) complex on a magnetic support for biomimetic carbon dioxide sequestration

• Published in: Journal of molecular catalysis. B, Enzymatic Enzymatic, 2012-10, Vol.82, p.37-45
• Main Authors: Sahoo, Prakash C., Jang, Young-Nam, Lee, Seung-Woo
• Format: Article
• Language: English
• Subjects: acetates; Artificial Zn-histidine complex; biocatalysis; Bioconversions. Hemisynthesis; Biological and medical sciences; Biomimetic CO2 sequestration; biomimetics; Biotechnology; carbon dioxide; carbonate dehydratase; Carbonic anhydrase; catalysts; CO2 Hydration; coatings; Fourier transform infrared spectroscopy; Fundamental and applied biological sciences. Psychology; hydrolysis; Immobilization; Iron oxide; magnetic fields; magnetic materials; Methods. Procedures. Technologies; physicochemical properties; reflectance spectroscopy; storage quality; temperature; thermal analysis; transmission electron microscopy; vibration; X-ray diffraction; zinc
• ISSN: 1381-1177; 1873-3158
• DOI: 10.1016/j.molcatb.2012.05.020

[Display omitted] ► The enzyme carbonic anhydrase and an artificial Zn(II)-His complex were immobilized onto CS/SiO2/γ-Fe2O3. ► The immobilized catalysts were found to be stable and magnetically separable from solution. ► These catalysts display accelerated CO2 hydration in aqueous solution. ► Reusability studies suggest that both immobilized CA and immobilized Zn-His retained significant activity after 10 cycles of use. The bio-catalytic activity of carbonic anhydrase (CA) immobilized on a Chitosan/SiO2/γ-Fe2O3 composite support (“/” means surface coating) was investigated. In addition, an artificial Zn(II)-model complex (Zn-His) was synthesized and immobilized on Chitosan/SiO2/γ-Fe2O3 to study its catalytic activity for carbon dioxide (CO2) hydration. The core magnetic material (γ-Fe2O3) in the support induced an easy recovery of the catalyst by the use of a magnetic field. The physicochemical properties of the support were determined by X-ray diffraction spectroscopy (XRD), vibration sample magnetometry (VSM), field mission-scanning electron microscopy (FE-SEM), field mission-scanning transmission electron microscopy (FE-TEM) and Fourier transform infrared (FTIR) spectroscopy. The Zn(II)-His complex was characterized by elemental analysis, Ultraviolet–visible diffuse reflectance spectroscopy (UV–vis DRS), and FTIR spectroscopic methods. The catalytic performances of the CA and zinc complex were studied for para-nitrophenyl acetate (p-NPA) hydrolysis by UV–vis spectroscopy. The Michaelis constant (Km) for the free CA, free Zn-histidine complex, immobilized CA and immobilized Zn-histidine complex were found to be 9.54, 19.46, 13.87 and 26.01mM, respectively, while the overall activity (Kcat/Km) for these four catalysts were 453.2, 91.36, 303.2, and 52.32M−1s−1, respectively. The thermal analysis and storage stability test results indicates that free and immobilized Zn-His complex retain significantly higher activity at elevated temperature and can be stored for a longer period compared with the free and immobilized CA. Both immobilized CA and immobilized Zn-His complex were investigated for the biocatalytic hydration of CO2. Reusability studies suggest that both immobilized CA and immobilized Zn-His retained significant activity after 10 cycles of use.