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Öğe Carboligation reactions catalyzed by benzaldehyde lyase (BAL, EC 4.1.2.38) covalently attached to epoxysilane modified Fe3O4@SiO2 nanoparticles(Amer Chemical Soc, 2011) Tural, Bilsen; Turan, Ilke Simsek; Celebi, Bulent; Yalinkilic, Ibrahim; Demir, Ayhan S.[Abstract Not Available]Öğe Carboligation reactions mediated by benzoylformate decarboxylase immobilized on a magnetic solid support(Wiley, 2013) Tural, Bilsen; Tural, Servet; Demir, Ayhan S.; 0000-0001-7555-2481; 0000-0003-2479-9438In this study, magnetic nanoparticles (Fe3O4, magnetite) with immobilized metal affinity ligands (MSS) were prepared and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FTIR), and vibrating-sample magnetometer (VSM) methods for purification and immobilization of the histidine-tagged recombinant benzoylformate decarboxylase (BFD). The MSS support was shown to be eligible for selective binding of HIS-tagged BFD by SDS-page analysis. Loading capacity of the MSS support was determined as 43.6 +/- 1.1mg/g. The regeneration ability for protein binding was also studied. An immobilized BFD was tested to catalyze benzoin condensation and representative cross acyloin reaction. Conversion and enantiomeric excess values were comparable with that of free enzyme catalyzed reactions. (C) 2013 Wiley Periodicals, Inc.Öğe Carboligation reactions with benzaldehyde lyase immobilized on superparamagnetic solid support(Royal Soc Chemistry, 2009) Sopaci, S. Betuel; Turan, Ilke Simsek; Tural, Bilsen; Volkan, Muervet; Demir, Ayhan S.Histidine-tagged recombinant benzaldehyde lyase (BAL, EC 4.1.2.38) was efficiently immobilized to surface-modified magnetic particles with affinity ligand binding. In addition to conventional benzoin condensation reactions, two important representative BAL-catalyzed carboligation reactions, were also performed with this magnetically responsive biocatalyst. The results obtained from the carboligation reactions that were performed with this simple and convenient heterogenous biocatalyst were comparable to that of free-enzyme-catalyzed reactions.Öğe Carboligation reactivity of benzaldehyde lyase (BAL, EC 4.1.2.38) covalently attached to magnetic nanoparticles(Pergamon-Elsevier Science Ltd, 2013) Tural, Bilsen; Turan, Ilke Simsek; Tural, Servet; Celebi, Bulent; Demir, Ayhan S.Epoxy-functionalized Fe3O4-SiO2 core-shell magnetic nanoparticles (epoxy-M-support) were prepared by modification with glycidyloxypropyltrimethoxysilane (GPTMS) and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and fourier transform infrared spectroscopy (FTIR) methods. Pure histidine-tagged recombinant benzaldehydelyase (BAL, EC 4.1.238) was efficiently immobilized onto the epoxy-M-support with covalent binding. An immobilized BAL epoxy-M-support system was tested to catalyze the self and cross condensation reactions of aldehydes, and the kinetic resolution of racemic acyloins. The acyloin products were obtained in high yield and with high enantiomeric excesses (>= 98% ee). The carboligation reactivity of the immobilized enzyme was comparable to that of free enzyme-catalyzed reactions. The covalent immobilization offers high enzyme activity and stability (at least 5 repeats without losing its activity). (C) 2013 Elsevier Ltd. All rights reserved.Öğe Manganese(III) acetate mediated oxidation of 1-alkyl-1H-indole and 9-methyl-9H-carbazole derivatives(Arkat Usa Inc, 2008) Demir, Ayhan S.; Tural, ServetManganese(III) acetate mediated oxidation of 1-alkyl-1H-indole and 9-methyl-9H-carbazole was studied. 1-Methyl-1H-indole gives the 1-acetoxymethyl derivative with good yield. 1-Methyl- 2-phenyl-1H-indole furnished the oxidation of the methyl group and C-3 of indole to obtain the corresponding acetoxy derivatives. 1-ethyl-2-phenyl derivative only furnished the C-3 acetoxylation product. 1,2-Dimethyl-1H-indole furnished oxidation on both of the methyl groups. The major products are 1-methyl-1H-indole-2-carbaldehyde and 1-methyl-2diacetoxymethyl- 1H-indole. Manganese(III) acetate oxidation of 9-methyl-9H-carbazole furnished (9H-carbazol-9-yl) methanol in good yield.Öğe Preparation and characterization of surface modified ?-Fe2O3 (maghemite)-silica nanocomposites used for the purification of benzaldehyde lyase(Pergamon-Elsevier Science Ltd, 2011) Tural, Bilsen; Sopaci, S. Betul; Ozkan, Necati; Demir, Ayhan S.; Volkan, Murvetgamma-Fe2O3 (maghemite)-silica nanocomposite particles were synthesized using a sol-gel method. The condensation products of 3-glycidoxy propyltrimethoxy silane (GPTMS) and nitrilotriacetic acid (NTA) were introduced onto the surfaces of the gamma-Fe2O3 silica nanocomposite particles and subsequently, these modified surfaces were complexed with cobalt (Co+2) metal ions. A possibility of using these surface modified gamma-Fe2O3-silica particles for the purification of 6 x histidine tagged recombinant benzaldehyde lyase (BAL, EC 4.1.2.38) based on magnetic separation was investigated. X-ray diffraction (XRD), thermal analysis, and vibrating sample magnetometry (VSM) methods were used to characterize the surface modified superparamagnetic gamma-Fe2O3 (maghemite)-silica nanoparticles. XRD (Scherer's equation) results indicate that the primary particle size of maghemite was around 11 nm. Magnetic characterization results confirmed that the gamma-Fe2O3 (maghemite)-silica nanoparticles were superparamagnetic. According to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) results, these superparamagnetic nanoparticles specifically capture 6 x His-tagged BAL from crude extract of Escherichia coli (E. coli) BL21(DE3)pLysS/BAL(HIS). This study shows that the surface modified gamma-Fe2O3 (maghemite)-silica nanoparticles are eligible for immobilized metal-ion affinity adsorption for histidine tagged recombinant proteins with its high capacity (3.16 +/- 0.4 mg/g) and selectivity. (C) 2011 Elsevier Ltd. All rights reserved.Öğe Purification and covalent immobilization of benzaldehyde lyase with heterofunctional chelate-epoxy modified magnetic nanoparticles and its carboligation reactivity(Elsevier Science Bv, 2013) Tural, Bilsen; Tural, Servet; Ertas, Erdal; Yalinkilic, Ibrahim; Demir, Ayhan S.In this work, histidine-tagged recombinant benzaldehyde lyase from Pseudomonas fluorescens Biovar I (BAL, EC 4.1.2.38) was immobilized on the magnetically responsive epoxy-chelate magnetic support following a two-step mechanism; that is, the protein is physically adsorbed and then the covalent bonding takes place. This mechanism has been exploited to combine the selectivity of metal chelate affinity chromatography with the covalent immobilization capacity of epoxy supports. In this way, it has been possible to accomplish, in a simple manner, the purification, immobilization, and stabilization of a histidine-tagged recombinant benzaldehyde lyase. To fulfill this objective we prepared and characterized a multifunctional Co2+-IDA-epoxy functionalized the silica coated magnetic nanoparticles (SCMPs) which are modified with glycidyloxypropyltrimethoxysilane (GPTMS) and iminodiacetic acid (IDA). To test immobilized BAL, benzoin condensation reaction was performed with this magnetically responsive biocatalyst. The results obtained from the carboligation reaction that was performed with this simple and convenient heterogeneous biocatalyst were comparable to that of free-enzyme-catalyzed reaction. Additional advantages are its reusability and it is easy to work with. (c) 2013 Elsevier B.V. All rights reserved.Öğe Selective one-pot synthesis of substituted pyrrole-3-phosphonates from ?-cyanomethyl-?-ketoesters(Pergamon-Elsevier Science Ltd, 2007) Demir, Ayhan S.; Tural, ServetA one-step synthesis of 5-alkoxypyrrole-3-phosphonates is presented starting from suitable alpha-cyanomethyl-beta-ketophosphonates. The key step in the synthesis involves a one-pot addition and heteroannulation sequence. The zinc perchlorate-catalyzed addition of alcohols to the nitrile carbon of alpha-cyanomethyl- beta-ketophosphonates followed by annulation furnished 5-alkoxypyrrole-3-phosphonates. The addition-annulation process is carried out in the presence of water and 4,5-dihydro-5-oxo-1H-pyrrole-3-phosphonates (pyrrolinones) are obtained in good yields. (C) 2007 Elsevier Ltd. All rights reserved.Öğe Separation and purification of benzoylformate decarboxylase via immobilization on magnetic solid support(Amer Chemical Soc, 2009) Tural, Bilsen; Sopaci, S. Betul; Demir, Ayhan S.[Abstract Not Available]
