Comparison of β-galactosidase immobilization by entrapment in and adsorption on poly(2-hydroxyethylmethacrylate) membranes
✍ Scribed by Baran, Türker; Arica, M. Yakup; Denizli, Adil; Hasirci, Vasif
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 287 KB
- Volume
- 44
- Category
- Article
- ISSN
- 0959-8103
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✦ Synopsis
b-Galactosidase was immobilized in/on poly(2-hydroxyethyl methacrylate) (pHEMA) membranes by two di †erent methods : adsorption on Cibacron F3GA derivatized pHEMA membranes (pHEMA-CB), and entrapment in the bulk of the pHEMA membranes. The maximum b-galactosidase adsorption on pHEMA-CB membranes was obtained as 95É6 kg cm~2 in 2É0 mg cm~3 enzyme solution. The adsorption phenomena appeared to follow a typical Langmuir isotherm. In the entrapment, an increase in b-galactosidase loading resulted in a consistent increase in membrane activity from 3É3 ] 10~2 to 17É8 ] 10~2 U cm~2 pHEMA membranes. The values for both immobil-K m ized b-galactosidase (adsorbed 0É32 mM and entrapped 0É81 mM) were higher than that of the free enzyme (0É26 mM). The optimum reaction temperature of the adsorbed enzyme was 5¡C higher than that of both the free and the entrapped enzyme. The optimum reaction pH was 7É5 for free and both immobilized preparations. After 15 successive uses the retained activity of the adsorbed and the entrapped enzymes was 80% and 95%, respectively. The storage stability of the enzyme was found to increase upon immobilization.