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KMID : 1094720140190050838
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Biotechnology and Bioprocess Engineering
2014 Volume.19 No. 5 p.838 ~ p.843
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Lipase immobilization on magnetic microspheres via spacer arms: Effect of steric hindrance on the activity
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Zhang Dong-Hao
Li Ya-Qiong
Peng Li-Juan
Chen Na
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Abstract
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Poly(styrene-acrylic acid) magnetic microspheres with an average diameter of 2 μm were successfully prepared and used as carriers to immobilize lipase. Lipase immobilized on microspheres with no spacer arm exhibited low activities, which were attributed to steric hindrance on the lipase conformation. To avoid steric effects, ethylenediamine and poly(ethylene glycol) (PEG) 400/800/4000 were utilized as spacer arms to bind the lipase to the microspheres. The immobilized lipase activities were improved using PEG 800/4000 as a spacer arm. Furthermore, the influence of enzyme loading on lipase activity was investigated, and the results indicated that enzyme overloading could exert steric effect on lipase activity. The degree of PEG modification was demonstrated to affect lipase activity because excess PEG on the surface of microspheres could interact with lipase due to its mobility, consequently reducing lipase activity.
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KEYWORD
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magnetic microspheres, lipase immobilization, steric hindrance, poly(ethylene glycol) 800, spacer arm
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