title: Immobilization and Characterization of Penicillin G Acylase (PGA) Immobilized on Magnetic Ni₀.₅Zn₀.₅Fe₂O₄ Nanoparticles.
abstract: Magnetic Ni₀.₅Zn₀.₅Fe₂O₄ nanoparticles were prepared via the solution combustion process and their microstructure and magnetic properties were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The as-prepared magnetic Ni₀.₅Zn₀.₅Fe₂O₄ nanoparticles are characterized with average grain size of about 20 nm and magnetization of 90.3 Am²/kg. The surface of magnetic Ni₀.₅Zn₀.₅Fe₂O₄ nanoparticles was modified by use of sodium silicate and N-(3-Dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride, and the penicillin G acylase (PGA) was successfully immobilized on the surface-modified magnetic Ni₀.₅Zn₀.₅Fe₂O₄ nanoparticles. The results show that the activity for the immobilized PGA is affected less by pH and temperature than that for the free PGA, and the immobilized PGA exhibits a high effective activity, good stability of enzyme catalyst. This immobilized PGA on magnetic Ni₀.₅Zn₀.₅Fe₂O₄ nanoparticles can be separated from the solution by the external magnetic field for cyclic utilization, and they could retain about 70% of initial enzyme activity after 11 consecutive operations. The kinetic parameters (Km and Vmax) were determined, and the value of Km for the immobilized PGA (204.53 mmol/L) is higher than that of the free enzyme (3.50 mmol/L), while Vmax (1.93 mmol/min) is also larger than that of the free enzyme (0.838 mmol/min).
authors.forename: Ruijiang
authors.initials: R
authors.lastname: Liu
authors.forename: Jiawen
authors.initials: J
authors.lastname: Fan
authors.forename: Yewang
authors.initials: Y
authors.lastname: Zhang
authors.forename: Peng
authors.initials: P
authors.lastname: Wang
authors.forename: Xiangqian
authors.initials: X
authors.lastname: Shen
mesh_terms: D004800:Enzymes, Immobilized / Q000737:chemistry*; D005290:Ferric Compounds / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry*; D009532:Nickel / Q000737:chemistry*; D010399:Penicillin Amidase / Q000737:chemistry*; D015032:Zinc / Q000737:chemistry*
chemical_list: D004800:Enzymes, Immobilized; D005290:Ferric Compounds; C000499:ferric oxide; D009532:Nickel; D010399:Penicillin Amidase; D015032:Zinc