کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1387176 | 982555 | 2010 | 8 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Covalent immobilization and thermodynamic characterization of pullulanase for the hydrolysis of pullulan in batch system Covalent immobilization and thermodynamic characterization of pullulanase for the hydrolysis of pullulan in batch system](/preview/png/1387176.png)
Pullulanase showed significant improvement in thermal stability after covalent immobilization on Duolite XAD761. Optimum temperature of immobilized enzyme was 60 °C, which was 10 °C higher than the free enzyme. Apparent Km values for pullulan, soluble starch and dextran were 4.4, 20 and 50 mg mL−1, respectively. Mn2+ and Ca2+ showed 2.0- and 2.2-fold increase in enzyme activity. Activation energy (Ea) of immobilized biocatalyst was 22.38 kJ mol−1. Thermodynamic parameters (ΔH*, ΔG*, ΔS*) for irreversible inactivation of immobilized pullulanase at different temperatures (60–70 °C) were also determined. D-value was maximum (95.95 h) at 60 °C and temperature quotient (Q10) was 1.29. Immobilized biocatalyst was effectively used for pullulan hydrolysis in a batch system. Stationary phase in hydrolysis (95.70 ± 1.36%) was reached after 300 min at 125 rpm. Pullulan hydrolysis yielded 4.21 ± 0.06% reducing sugars under optimal conditions. Immobilized biocatalyst was successfully recycled for 33 batches, but the enzyme activity was reduced to half after 25th cycle.
Journal: Carbohydrate Polymers - Volume 81, Issue 2, 11 June 2010, Pages 252–259