AUTHOR=Ni Yun , Lv Zhixiang , Wang Zhou , Kang Shouyu , He Dawei , Liu Ruijiang 

TITLE=Immobilization and Evaluation of Penicillin G Acylase on Hydroxy and Aldehyde Functionalized Magnetic α-Fe2O3/Fe3O4 Heterostructure Nanosheets

JOURNAL=Frontiers in Bioengineering and Biotechnology

VOLUME=9

YEAR=2022

URL=https://www.frontiersin.org/journals/bioengineering-and-biotechnology/articles/10.3389/fbioe.2021.812403

DOI=10.3389/fbioe.2021.812403

ISSN=2296-4185

ABSTRACT=<p>Magnetic α-Fe<sub>2</sub>O<sub>3</sub>/Fe<sub>3</sub>O<sub>4</sub> heterostructure nanosheets were fabricated via hydrothermal calcination. The activity of penicillin G acylase (PGA), which was covalently immobilized onto silica-decorated heterostructure nanosheets, achieved the highest activity of 387.03 IU/g after 18 h of incubation with 0.1 ml of PGA. In contrast, the activity of free PGA reached the highest level when the temperature was 45°C with a pH of 8.0. However, the activity of free PGA changed more dramatically than immobilized PGA as the relative conditions changed. Moreover, the Michaelis–Menten constant (K<sub>m</sub>) and reusability of immobilized PGA were also explored. The results showed that free PGA K<sub>m</sub> and maximum rate (V<sub>max</sub>) were 0.0274 M and 1.167 μl/min, respectively. K<sub>m</sub> and V<sub>max</sub> values of immobilized PGA were 0.1082 M and 1.294 μl/min, respectively. After 12 cycles of repetitive use, immobilized PGA remained approximately 66% of its initial activity, indicating that the PGA immobilized onto the heterostructure nanosheets showed better stability and reusability than free PGA.</p>