期刊
COLLOIDS AND SURFACES B-BIOINTERFACES
卷 189, 期 -, 页码 -出版社
ELSEVIER
DOI: 10.1016/j.colsurfb.2020.110874
关键词
Magnetic microspheres; Polyethyleneimine; Lipase; Crosslink; Conformation
资金
- National Natural Science Foundation of China [21878065]
- Natural Science Foundation of Hebei Province, China [B2015201167]
- Natural science interdisciplinary research program of Hebei University [DXK201911]
Here, PEI@PMMA microspheres were prepared by grafting polyethyleneimine (PEI) on poly(methyl methacrylate) (PMMA) magnetic microspheres and successfully used to immobilize lipase. The results showed that PEI@PMMA microspheres had strongly adsorbed lipase (49.1 mg/g microsphere) via electrostatic attraction. To prevent lipase shedding, the adsorbed lipase was further crosslinked with PEI on microspheres using glutaraldehyde as crosslinker. Consequently, PEI-crosslinked lipase (2.14 U/mg) exhibited 2.6 times and 1.4 times higher activity respectively than the directly covalent lipase (0.82 U/mg) and the crosslinked lipase aggregates (1.57 U/mg), which was close to the activity of adsorbed lipase (2.20 U/mg). Conformational analysis from FTIR spectroscopy showed that PEI-crosslinked lipase retained its natural structure well. And the alpha-helix structure seemed to play a key role in enhancing lipase activity. Furthermore, the effects of various parameters on crosslinking reaction were investigated. Also, PEI-crosslinked lipase revealed higher pH and thermal stability. The Michaelis constant (K-m) was increased and the optimum temperature of lipase was widened observably after crosslinking with PEI on PEI@PMMA magnetic microspheres.
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