Person: DEMİR, SERAP
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DEMİR
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SERAP
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Publication Metadata only Xylanase immobilization on functionalized polyaniline support by covalent attachment(WILEY-V C H VERLAG GMBH, 2013) KAHRAMAN, MEMET VEZİR; Madakbas, Seyfullah; Danis, Ozkan; Demir, Serap; Kahraman, Memet VezirChemically synthesized polyaniline (PANI) was used as polymeric support for xylanase immobilization. The polymer was first activated with glutaraldehyde and then xylanase was successfully immobilized. Xylanase bound polymer was characterized using FTIR. The optimum pH of the immobilized enzyme was at pH 5, which was shifted 1.0?pH unit to the acidic region when compared to the free enzyme. Thermal stability of the xylanase was improved with the immobilization. The characteristic properties of the immobilized and native enzyme, such as kinetic activity, reusability and storage stability were also studied at optimum pH and temperature. Immobilized enzyme exhibited better reusability and storage stability than the free one. Vmax values for the free and immobilized enzymes were calculated as 1.44 and 0.44?mg/mL/min, respectively. The Km values for the immobilized xylanase were found to be lower.Publication Metadata only Covalent immobilization of a-amylase onto thermally crosslinked electrospun PVA/PAA nanofibrous hybrid membranes(WILEY, 2013) KAHRAMAN, MEMET VEZİR; Basturk, Emre; Demir, Serap; Danis, Ozkan; Kahraman, Memet VezirPoly(vinyl alcohol)/poly(acrylic acid) (PVA/PAA) nanofibers with the fiber diameter of 100150 nanometers were fabricated by electrospinning. PVA/PAA nanofibers were crosslinked by heat-induced esterification and resulting nanofiber mats insoluble in water. a-Amylase was covalently immobilized onto the PVA/PAA nanofiber surfaces via the activation of amine groups in the presence of 1,1'-carbonyldiimidazole. The immobilized a-amylase has more resistance to temperature inactivation than that of the free form and showed maximum activity at 50 degrees C. pH-dependent activities of the free and immobilized enzymes were also investigated, and it was found that the pH of maximum activity for the free enzyme was 6.5, while for the optimal pH of the immobilized enzyme was 6.0. Reuse studies demonstrated that the immobilized enzyme could reuse 15 times while retaining 81.7% of its activity. Free enzyme lost its activity completely within 15 days. Immobilized enzyme lost only 17.1% of its activity in 30 days. (C) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2012