Akademik Veri Yönetim Sistemi
BIOCHEMICAL ENGINEERING JOURNAL, cilt.49, sa.2, ss.159-164, 2010 (SCI-Expanded)
Novel magnetic nanospheres with an average size of 118 nm utilizing N-methacryloyl-(L)-cysteine methyl ester (MAC) as a monomer were prepared by surfactant free emulsion polymerization of 2-hydroxyethyl methacrylate (HEMA) and MAC conducted in an aqueous dispersion medium. MAC was synthesized using methacryloyl chloride and L-cysteine methyl ester. L-Cysteine groups of the mag-poly(HEMA-MAC) nanospheres were chelated with Fe3+ ions. Specific surface area of the nonporous nanospheres was found to be 2452 m(2)/g. Mag-poly(HEMA-MAC)-Fe3+ nanospheres contained 0.81 mmol sulphur/g polymer were used in the adsorption of catalase in batch system. Using an optimized adsorption protocol, a very high loading of 820 mg catalase/g nanosphere was obtained. The adsorption phenomena appeared to follow a typical Langmuir isotherm. The immobilized catalase has more resistence to temperature inactivation than that of their free form. The optimum pH value of catalase was not affected by the immobilization reaction, but the pH profile was broadened for the immobilized enzyme. Kinetic parameters were determined for immobilized catalase as well as for the free enzyme. The values of the Michaelis constant K-m of catalase were significantly smaller (ca. 2.5 times) upon immobilization, indicating increased affinity of the enzyme for its substrate, whereas V-max value of free catalase was higher than that of the immobilized enzyme. It was also observed that enzyme could be repeatedly adsorbed and desorbed on the mag-poly(HEMA-MAC)-Fe3+ nanospheres without loss of adsorption capacity or enzymatic activity. (C) 2009 Elsevier B.V. All rights reserved.