Immobilization of laccase in poly(acrylamide-acrylic acid)/alginate, poly(acrylamide-itaconic acid)/alginate, poly(acrylamide-acrylic acid)/K-carrageenan, poly(acrylamide-itaconic acid)/K-carrageenan hydrogels

In this study, laccase enzyme was immobilized using entrapment method in poly(acrylamide-acrylic acid)/Alginate, P(AAm-AA)/Alj, poly(acrylamide-itaconic acid)/Alginate, P(AAm-IA)/Alj, poly(acrylamide-acrylic acid)/K-carrageenan, P(AAm-AA)/K-kar, poly(acrylamide-itaconic acid)/K-carrageenan, P(AAm-IA)/K-kar semi-interpenetrating network (semi-IPNs). Optimum temperature was determined as 40 oC for free laccase and immobilized laccases. Optimum pH was determined between 5,0-6,0 for free laccase and immobilized laccases. After 42 days of storage at 4 oC, free laccase and P(AAm-AA)/Alj, P(AAm-IA)/Alj, P(AAm-AA)/K-kar, P(AAm-IA)/K-kar immobilized enzymes retained %55 and % 83, % 94, % 94, % 83 of their original activities, respectively. P(AAm-AA)/Alj, P(AAm-IA)/Alj, P(AAm-AA)/K-kar, P(AAm-IA)/K-kar immobilized enzymes used repeatedly 10 times in a day and they were retained %80, % 50 % 62, %52 of their original activities, respectively. Km and Vmax were calculated for free laccase as Km value is 0,0073 mM, Vmax value is 1,04x10-3 mM.min-1 and for P(AAm-AA)/Alj, P(AAm-IA)/Alj, P(AAm-AA)/K-kar, P(AAm-IA)/K-kar immobilized laccases Km values are 0,0196 mM, 0,0116 mM, 0,0252 mM and 0,0108 mM and Vmax values are 3,29x10-3 mM.min-1, 5,22x10-3 mM.min-1, 6,80x10-3 mM.min-1 and 4,40x10-3 mM.min-1, respectively. Inactivation rate constants (ki) of immobilized laccases at 30 °C and 50 °C were found between 0,0006 min-1-0,0014 min-1 and 0,0012 min-1- 0,0031 min-1. Percent decolorization of methyl orange by free enyzme and enyzmes immobilized in P(AAm-AA)/Alj, P(AAm-IA)/Alj, P(AAm-AA)/K-kar, P(AAm-IA)/K-kar were found as %63 and %43, %46, %36, %35. Percent decolorization of methyl orange in the presence of mediator by free enyzme and enyzmes immobilized in P(AAm-AA)/Alj, P(AAm-IA)/Alj, P(AAm-AA)/K-kar, P(AAm-IA)/K-kar were found as %73 and %70, %72, %69, %71.