title: Immobilization of laccase in kappa-carrageenan based semi-interpenetrating polymer networks.
abstract: Laccase enzyme (L) was immobilized by entrapment into semi-interpenetrating polymer networks (semi-IPNs) prepared from kappa-carrageenan with either poly(acrylamide-acrylic acid) [P(AAm-AA)/kappa-car] or poly(acrylamide-itaconic acid) [P(AAm-IA)/kappa-car]. For both systems, immobilized enzymes achieved the same optimum values observed for free enzyme (pH=5.0 and T=40 degrees C), except for P(AAm-IA)/kappa-car system there was a shift to 5.5 in optimum pH value. At the end of 42 days of storage immobilized enzymes retained more than 80% of their original activities while the retained activities of both systems after 10 uses in batch type application were found to be higher than 50%. K(m) values were calculated as 2.52x10(-2) mM and 1.08x10(-2) mM and V(max) values were found as 6.8x10(-3) mM min(-1) and 4.4x10(-3) mM min(-1), for P(AAm-AA)/kappa-car-L and P(AAm-IA)/kappa-car-L, respectively. When methyl orange containing solutions (10 mg/L) were treated with the immobilized laccases (68.2U), enzymatic decolorization of methyl orange in 6 h was achieved to the level of 35% for both systems. Supplementing the reaction medium with ABTS as the redox mediator increased this value to about 70%. These initial results show that, laccase containing semi-IPNs can find some applications in decolorization of the industrial wastes.
authors.affiliation: Department of Chemistry, Faculty of Arts and Sciences, Gazi University, Teknikokullar, Ankara, Turkey.
authors.forename: Y Gizem
authors.initials: YG
authors.lastname: Makas
authors.forename: N Ayca
authors.initials: NA
authors.lastname: Kalkan
authors.forename: Serpil
authors.initials: S
authors.lastname: Aksoy
authors.forename: Haydar
authors.initials: H
authors.lastname: Altinok
authors.forename: Nesrin
authors.initials: N
authors.lastname: Hasirci
mesh_terms: D000327:Adsorption; D001391:Azo Compounds / Q000737:chemistry* / Q000302:isolation & purification; D001672:Biocompatible Materials / Q000737:chemistry*; D002351:Carrageenan / Q000737:chemistry*; D004789:Enzyme Activation; D004800:Enzymes, Immobilized / Q000737:chemistry; D042845:Laccase / Q000737:chemistry*; D008422:Materials Testing; D011108:Polymers / Q000737:chemistry*; D016062:Porosity
chemical_list: D001391:Azo Compounds; D001672:Biocompatible Materials; D004800:Enzymes, Immobilized; D011108:Polymers; C100258:methyl orange; D002351:Carrageenan; D042845:Laccase