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Li Y.,Jimei University | Xiao Q.,Jimei University | Ni H.,Jimei University | Ni H.,Fujian Provincial Key Laboratory of Food Microbiology and Enzyme Engineering | And 7 more authors.
Journal of Computational and Theoretical Nanoscience | Year: 2016

Arylsulfatase, one of a few enzymes that can enhance the gelling strength of agar by cleaving the sulfate ester bonds in agar, was covalently immobilized with carboxyl functioned magnetic nanoparticles (CMNPs). The resultant CMNPs and immobilized arylsulfatase were characterized by transmission electron microscopy (TEM), Dynamic Light scattering (DLS), X-ray diffraction (XRD), vibrating sample magnetometry (VSM) and thermogravimetric analysis (TGA). The TEM result indicated that the CMNPs and immobilized arylsulfatase had a similar mean particle size of 10 nm. The arylsulfatase-CMNPs had a mean diameter of 1200 nm in aqueous solution determined by the DLS, which was much bigger than the CMNPs (433.6 nm). The different sizes demonstrated that the arylsulfatase was coated on CMNPs successfully. XRD showed that diffraction patterns of the CMNPs and arylsulfatase-CMNPs were close to the standard XRD pattern of Fe3O4. Saturation magnetizations were 52.1 emu/g for carriers and 47.9 emu/g for immobilized arylsulfatase, which indicated that the particles had superparamagnetic characteristics. The TGA revealed that the amount of arylsulfatase bound to the surface of CMNPs was 5.65%. The arylsulfatase exhibited better thermal stability and reusability after immobilization, the immobilized arylsulfatase can retain more than 50% enzyme activity up to the 9th cycle. © Copyright 2016 American Scientific Publishers All rights reserved.

Wu C.,Jimei University | Wu C.,Fujian Provincial Key Laboratory of Food Microbiology and Enzyme Engineering | Wu C.,Xiamen Key Laboratory of Marine Functional Food | Xu C.,Jimei University | And 12 more authors.
Bioresource Technology | Year: 2016

Tannase from Aspergillus tubingensis was immobilized onto carboxyl-functionalized Fe3O4 nanoparticles (CMNPs), and conditions affecting tannase immobilization were investigated. Successful binding between CMNPs and tannase was confirmed by Fourier transform infrared spectroscopy and thermogravimetric analysis. Vibrating sample magnetometry and X-ray diffraction showed that the CMNPs and immobilized tannase exhibit distinct magnetic responses and superparamagnetic properties. Free and immobilized tannase exhibited identical optimal temperatures of 50°C and differing pH optima at 6 and 7, respectively. The thermal, pH, and storage stabilities of the immobilized tannase were superior to those of free tannase. After six cycles of catalytic hydrolysis of propyl gallate, the immobilized tannase maintained over 60% of its initial activity. The Michaelis constant (Km) of the immobilized enzyme indicated its higher affinity for substrate binding than the free enzyme. © 2016 Elsevier Ltd.

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