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Synthesis and characterization of thermo-responsive poly-N-isopropylacrylamide bioconjugates for application in the formation of galacto-oligosaccharides

Paper ID Volume ID Publish Year Pages File Format Full-Text
17229 42653 2014 10 PDF Available
Title
Synthesis and characterization of thermo-responsive poly-N-isopropylacrylamide bioconjugates for application in the formation of galacto-oligosaccharides
Abstract

•Thermo-responsive poly-N-isopropylacrylamide-β-galactosidase was synthesized.•PNIPAAm-β-galactosidase had lower LCST than PNIPAAm polymer.•PNIPAAm-β-galactosidase showed higher stability than native enzyme.•Activity of PNIPAAm bioconjugate improved in the presence of ethylene glycol.•Galacto-oligosaccharides were synthesized with PNIPAAm-β-galactosidase.

The study demonstrates the properties of conjugation of β-galactosidase with a thermo-responsive polymer, poly-N-isopropylacrylamide (PNIPAAm) in comparison to a non-responsive polymer, poly-acrylamide (PAAm). The maximum formation of bioconjugate (PNIPAAm-β-galactosidase) was 75% (yield) with 50% chemically modified enzyme (using itaconic anhydride). The process of bioconjugation (bioconjugate concentration: 7.4%) decreases lower critical solution temperature from 32.5 °C (with pure PNIPAAm) to 26.5 °C. The effect of temperature on the activities of PNIPAAm-β-galactosidase, PAAm-β-galactosidase and native enzyme was also compared. At 70 °C, the maximum activity was observed for PNIPAAm-β-galactosidase while for others it was at 60 °C. However, the effect of pH was insignificant on activities of both the bioconjugates than the native enzyme. The addition of ethylene glycol (20%, v/v) enhances the activity (by 45%) of PNIPAAm-β-galactosidase with no loss in stability; however; the trend is reversed with the addition of ethanol. Further, employing bioconjugates even up to 24 cycles of precipitation (at 40 °C) followed by re-dissolution (4 °C) around 90% of activity could be retained by PNIPAAm-β-galactosidase. The PNIPAAm-β-galactosidase also showed much-improved thermal and storage stabilities. A lower Michaelis–Menten constant (Km) was estimated with the PNIPAAm-β-galactosidase than the native enzyme as well as PAAm-β-galactosidase. Finally, PNIPAAm-β-galactosidase was tested to synthesize galacto-oligosaccharides from lactose solution.

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Keywords
Bioconjugate; Responsive polymer; Enzyme immobilization; Galacto-oligosaccharide; Poly-N-isopropylacrylamide
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Synthesis and characterization of thermo-responsive poly-N-isopropylacrylamide bioconjugates for application in the formation of galacto-oligosaccharides
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Publisher
Database: Elsevier - ScienceDirect
Journal: Enzyme and Microbial Technology - Volume 55, 5 February 2014, Pages 40–49
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us