期刊
JOURNAL OF MOLECULAR CATALYSIS B-ENZYMATIC
卷 61, 期 3-4, 页码 208-215出版社
ELSEVIER
DOI: 10.1016/j.molcatb.2009.07.003
关键词
Magnetic Fe3O4 nanoparticle; Chitosan; beta-D-Galactosidase; Immobilization; Galactooligosaccharide
资金
- 863 Program
- Ministry of Science and Technology, China [2007AA10Z351, 2007AA100403]
- Nanjing Agricultural University [804066]
A novel and efficient immobilization of beta-D-galactosidase from Aspergillus oryzae has been developed by using magnetic Fe3O4-chitosan (Fe3O4-CS) nanoparticles as support. The magnetic Fe3O4-CS nanoparticles were prepared by electrostatic adsorption of chitosan onto the surface of Fe3O4 nanoparticles made through co-precipitation of Fe2+ and Fe3+. The resultant material was characterized by transmission electron microscopy. X-ray diffraction, Fourier transform infrared spectroscopy, vibrating sample magnetometry and thermogravimetric analysis. beta-D-Galactosidase was covalently immobilized onto the nanocomposites using glutaraldehyde as activating agent. The immobilization process was optimized by examining immobilized time, cross-linking time, enzyme concentration, glutaraldehyde concentration, the initial pH values of glutaraldehyde and the enzyme solution. As a result. the immobilized enzyme presented a higher storage, pH and thermal stability than the soluble enzyme. Calactooligosaccharide was formed with lactose as substrate by using the immobilized enzyme as biocatalyst, and a maximum yield of 15.5% (w/v) was achieved when about 50% lactose was hydrolyzed. Hence, the magnetic Fe3O4-chitosan nanoparticles are proved to be an effective support for the immobilization of beta-D-galactosidase. (C) 2009 Elsevier B.V. All rights reserved.
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