Fig 6 -

Thermal stability of free PGA (A) and immobilized PGA (B).</p

Fig 5 -

The catalytic capacity of free PGA (A) and immobilized PGA (B) at different temperatures, the effects of different pH on the activity of free PGA (C) and immobilized PGA (D).</p

Fig 7 -

The Michaelis constant of free and immobilized PGA (A), and the Repetitive availability of immobilized PGA (B).</p

The raw data reports generated by the measuring instruments during the experiment are presented in the worksheet in support Information 1, which details the raw data under each test target.

The original data measured and calculated during the experiment were made into tables named after the experiment content and presented in supporting Information 2. Details of the data designed in all experiments can be found in the supporting documentation. (XLSX)</p

Fig 2 -

Transmission electron microscopy (TEM) image (A), selected area electron diffraction (SAED) spectrum (B), X-ray diffraction (XRD) pattern (C), XRD standard card (D), vibrating sample magnetometry (VSM) curve (E), and Nitrogen adsorption isotherm and pore distribution map (F) of the magnetic Ni0.4Cu0.5Zn0.1Fe2O4 nanoparticles prepared at 400°C for 2.0 h with a heating rate of 3°C·min-1.</p

The material preparation and immobilization process.

The material preparation and immobilization process.</p

S1 File -

With the emergence of penicillin resistance, the development of novel antibiotics has become an urgent necessity. Semi-synthetic penicillin has emerged as a promising alternative to traditional penicillin. The demand for the crucial intermediate, 6-aminopicillanic acid (6-APA), is on the rise. Enzyme catalysis is the primary method employed for its production. However, due to certain limitations, the strategy of enzyme immobilization has also gained prominence. The magnetic Ni0.4Cu0.5Zn0.1Fe2O4 nanoparticles were successfully prepared by a rapid-combustion method. Sodium silicate was used to modify the surface of the Ni0.4Cu0.5Zn0.1Fe2O4 nanoparticles to obtain silica-coated nanoparticles (Ni0.4Cu0.5Zn0.1Fe2O4-SiO2). Subsequently, in order to better crosslink PGA, the nanoparticles were modified again with glutaraldehyde to obtain glutaraldehyde crosslinked Ni0.4Cu0.5Zn0.1Fe2O4-SiO2-GA nanoparticles which could immobilize the PGA. The structure of the PGA protein was analyzed by the PyMol program and the immobilization strategy was determined. The conditions of PGA immobilization were investigated, including immobilization time and PGA concentration. Finally, the enzymological properties of the immobilized and free PGA were compared. The optimum catalytic pH of immobilized and free PGA was 8.0, and the optimum catalytic temperature of immobilized PGA was 50°C, 5°C higher than that of free PGA. Immobilized PGA in a certain pH and temperature range showed better catalytic stability. Vmax and Km of immobilized PGA were 0.3727 μmol·min-1 and 0.0436 mol·L-1, and the corresponding free PGA were 0.7325 μmol·min-1 and 0.0227 mol·L-1. After five cycles, the immobilized enzyme activity was still higher than 25%.</div

Fig 4 -

The standard curve of protein (A) and 6-APA (B), the effects of immobilization time (C) and PGA concentration (D) on the catalytic activity of the immobilized enzyme.</p

Fig 3 -

The EDS maps (A) and EDS spectrogram (B) of Ni0.4Cu0.5Zn0.1Fe2O4@SiO2-GA, FTIR spectra (C) of Ni0.4Cu0.5Zn0.1Fe2O4 nanoparticles (a), Ni0.4Cu0.5Zn0.1Fe2O4@SiO2 (b), Ni0.4Cu0.5Zn0.1Fe2O4@SiO2-GA (c) and Ni0.4Cu0.5Zn0.1Fe2O4@SiO2-GA-PGA (d), the HRTEM gram (D) and Lattice fringe picture (E) of Ni0.4Cu0.5Zn0.1Fe2O4@SiO2-GA, the docking pattern of penicillin G and PGA (F), and the molecular model of PGA (G).</p