Person: KAHRAMAN, MEMET VEZİR
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KAHRAMAN
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MEMET VEZİR
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Publication Metadata only Soybean oil based resin: A new tool for improved immobilization of alpha-amylase(WILEY, 2006) OGAN, AYŞE; Kahraman, MV; Kayaman-Apohan, N; Ogan, A; Gungor, AAcrylated epoxidized soybean resin has been utilized to immobilize the alpha-amylase via UV-curing technique. Among the numerous methods that exist for enzyme immobilization, entrapment and covalent binding are the focus of this study. The properties of immobilized enzyme were investigated and compared with those of the free enzyme. Upon immobilization by the two methods, the catalytic properties of the enzyme were not considerably changed as compared with that of nonimmobilized form; enzyme. The free enzyme lost its activity completely in 20 days, where as storage and repeated usage capability experiments demonstrated higher stability for the immobilized form. Immobilized enzyme prepared by attachment method possesses relatively higher activity compared with the activity of those obtained by entrapment method. (c) 2006 Wiley Periodicals, Inc.Publication Metadata only Covalent Immobilization of alpha-Amylase onto UV-Curable Coating(WILEY, 2009) KAHRAMAN, MEMET VEZİR; Yarar, Uemran; Kahraman, Memet VezirA UV-curable N-(4-sodiumsulfophenyl)maleimide monomer was synthesized, and its potential for enzyme binding was investigated. The bromine, which is used to activate the synthesized monomer for covalent attachments, has the advantage of giving reaction with the surface groups of enzyme under very mild conditions (0 degrees C, 30 min). In this procedure, sulfonyl bromide pendant monomer reacted with amino groups of the protein to form sulfonamide bonds. Polymeric support was prepaped by UV-curing technique. The water adsorption value was found to be less than 1%. The enzyme-bounding yield was found to be 68.18 +/- 4.20 mg/g monomer. The maximum activity was observed at pH 6.5. Immobilization did not change the pH-dependency of the enzyme activity. It was found that the optimum temperature for the free enzyme was similar to 30 degrees C, whereas it shifted to nearly 50 degrees C for the immobilized enzyme. Free enzyme lost its activity completely within 15 days. Immobilized enzyme lost only 30% of its activity in 30 days. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 114: 3716-3722, 2009Publication Metadata only Alpha-Amylase Immobilization on Epoxy Containing Thiol-Ene Photocurable Materials(KOREAN SOC MICROBIOLOGY & BIOTECHNOLOGY, 2013) ÇAKMAKÇI, EMRAH; Cakmakci, Emrah; Danis, Ozkan; Demir, Serap; Mulazim, Yusuf; Kahraman, Memet VezirThiol-ene polymerization is a versatile tool for several applications. Here we report the preparation of epoxide groups containing thiol-ene photocurable polymeric support and the covalent immobilization of alpha-amylase onto these polymeric materials. The morphology of the polymeric support was characterized by scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) coupled with SEM was used to explore the chemical composition. The polymeric support and the immobilization of the enzyme were characterized by FTIR analysis. SEM-EDS and FTIR results showed that the enzyme was successfully covalently attached to the polymeric support. The immobilization efficiency and enzyme activity of alpha-amylase were examined at various pH (5.0-8.0) and temperature (30-80 degrees C) values. The storage stability and reusability of immobilized alpha-amylase were investigated. The immobilization yield was 276 +/- 1.6 mg per gram of polymeric support. Enzyme assays demonstrated that the immobilized enzyme exhibited better thermostability than the free one. The storage stability and reusability were improved by the immobilization on this enzyme support. Free enzyme lost its activity completely within 15 days. On the other hand, the immobilized enzyme retained 86.7% of its activity after 30 days. These results confirm that alpha-amylase was successfully immobilized and gained a more stable character compared with the free one.Publication Metadata only UV-curable methacrylated/fumaric acid modified epoxy as a potential support for enzyme immobilization(ELSEVIER, 2007) KAHRAMAN, MEMET VEZİR; Kahraman, M. Vezir; Bayramoglu, Gulay; Kayaman-Apohan, Nilhan; Gungor, AtillaThe immobilization procedure of UV-curing coating is simple and causes less loss of enzymatic activity. UV-curable methacrylated/fumaric acid modified cycloaliphatic epoxide is here proposed as a rigid support material for covalent immobilization of a-amylase. The immobilized enzyme is analyzed in terms of bioactivity retention as a function of repeated use ability, pH, storage, as well as stability under various experimental conditions, taking starch as a substrate. The properties of immobilized enzyme were also compared with those of the free enzyme. The highest activity of free enzyme was obtained at pH 7.0 while this value was shifted to PH 7.5 for immobilized system. Optimum catalytic activity was observed at 30 degrees C, for both free and immobilized enzyme; however, the immobilized enzyme had a higher activity than the free one. The immobilized enzyme that was used 35 times in 8 h in repeated batch experiments demonstrated that about 73% of the enzyme activity was retained. The free enzyme lost all its activity with in 15 days. The retained activity of immobilized enzyme was found to be around 80%. The amount of bound alpha-amylase was found 94 mg per gram polymeric support material. (c) 2006 Published by Elsevier B.V.Publication Metadata only alpha-Amylase immobilization on functionalized glass beads by covalent attachment(ELSEVIER SCI LTD, 2007) KAHRAMAN, MEMET VEZİR; Kahraman, M. Vezir; Bayramoglu, Gulay; Kayaman-Apohan, Nilhan; Gungor, AtillaIn this study alpha-amylase was covalently immobilized onto phthaloyl chloride-containing amino group functionalized glass beads. In this procedure. amide bonds were formed between amino groups on the protein and acid chloride groups on the glass surface. The surface modified beads were characterized using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersion spectrum (EDS) and UV-Vis spectroscopy. Immobilization was successfully performed under very mild conditions (15 degrees C. 4 h). The amount of covalently bound alpha-amylase was found 25.2 +/- 3.1 mg/g glass support. The optimum pH value for the free amylase was at pH 6.5. The optimum pH of the immobilized enzyme was shifted 1.0 pH unit to the acidic region. The immobilized alpha-amylase exhibited better thermostability than the free one. The free enzyme lost all its activity with in 15 days. Covalently bound amylase was stable up to 5 days and lost only 20% of activity in 25 days. The covalently bound enzyme demonstrated more than 98% activitv after 6 runs and 81.4% activity after 25 runs. (c) 2007 Elsevier Ltd. All rights reserved.