title: Preparation Fe3O4@chitosan magnetic particles for covalent immobilization of lipase from Thermomyces lanuginosus.
abstract: Magnetic Fe3O4@chitosan nanoparticles were prepared by a simple in situ co-precipitation method and characterized by transmission electron microscope (TEM) and Fourier transform infrared spectroscopy (FTIR). The prepared Fe3O4@chitosan nanoparticles were used for covalent immobilization of lipase from Thermomyces lanuginosus by chemical conjugation after electrostatic entrapment (CCEE). The optimal immobilization conditions were obtained as follows: enzyme/support 19.8 mg/g, pH 5.0, time 4h and temperature 30 °C. Under these conditions, a high immobilization efficiency of 75% and a protein loading of 16.8 mg/g-support were obtained. Broad pH tolerance and high thermostability could be achieved by immobilization. The immobilized lipase retained 70% initial activity after ten cycles. Kinetic parameters Vmax and Km of free and immobilized lipase were determined as 5.72 mM/min, 2.26 mM/min and 21.25 mM, 28.73 mM, respectively. Ascorbyl palmitate synthesis with immobilized lipase was carried out in tert-butanol at 50 °C, and the conversion of ascorbic acid was obtained higher than 50%. These results showed that the immobilization of lipase onto magnetic chitosan nanoparticles by the method of CCEE is an efficient and simple way for preparation of stable lipase.
authors.affiliation: School of Pharmacy, Jiangsu University, Xuefu Rd. 301, Zhenjiang 212013, People's Republic of China.
authors.forename: Xiang-Yu
authors.initials: XY
authors.lastname: Wang
authors.affiliation: School of Pharmacy, Jiangsu University, Xuefu Rd. 301, Zhenjiang 212013, People's Republic of China.
authors.forename: Xiao-Ping
authors.initials: XP
authors.lastname: Jiang
authors.affiliation: School of Pharmacy, Jiangsu University, Xuefu Rd. 301, Zhenjiang 212013, People's Republic of China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Li
authors.affiliation: School of Pharmacy, Jiangsu University, Xuefu Rd. 301, Zhenjiang 212013, People's Republic of China.
authors.forename: Sha
authors.initials: S
authors.lastname: Zeng
authors.affiliation: School of Pharmacy, Jiangsu University, Xuefu Rd. 301, Zhenjiang 212013, People's Republic of China. Electronic address: zhangyewang@ujs.edu.cn.
authors.forename: Ye-Wang
authors.initials: YW
authors.lastname: Zhang
mesh_terms: D001203:Ascomycota / Q000201:enzymology*; D001205:Ascorbic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D048271:Chitosan / Q000138:chemical synthesis* / Q000737:chemistry; D003911:Dextrans / Q000138:chemical synthesis* / Q000737:chemistry; D004795:Enzyme Stability; D004800:Enzymes, Immobilized / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008049:Lipase / Q000378:metabolism*; D058185:Magnetite Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature; D013997:Time Factors
chemical_list: D003911:Dextrans; D004800:Enzymes, Immobilized; D058185:Magnetite Nanoparticles; D048271:Chitosan; D008049:Lipase; C065507:ferumoxides; D001205:Ascorbic Acid; C031226:6-O-palmitoylascorbic acid
keywords: Chemical conjugation after electrostatic entrapment; Chitosan; Immobilization; Lipase; Magnetic nanoparticles; Stability