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Öğe Enantioselective resolution of racemic flurbiprofen methyl ester by lipase encapsulated mercapto calix[4]arenes capped Fe3O4 nanoparticles(SPRINGER, 2017) Yildiz, Hasan; Ozyilmaz, Elif; Bhatti, Asif Ali; Yilmaz, MustafaThis work presents the synthesis of new mercapto calix[4]arenes derivatives (4 and 5). These derivatives were capped on Fe3O4 magnetic nanoparticles and subsequently encapsulated with Candida rugosa through sol-gel method to furnish enc-4 and enc-5, respectively, to enhance catalytic activity and enantioselectivity of lipase for hydrolysis reaction of racemic flurbiprofen methyl ester. Catalytic activity and enantioselectivity of enc-4 and enc-5 were assayed at different pH and temperature conditions and it was found that the resultant encapsulated enzyme exhibited higher thermal and operational stabilities compared to the free lipase in which enc-5 showed the excellent rate of enantioselectivity (E = 176) for S-flurbiprofen better than free lipase (E = 137) at pH 7 and 35 A degrees C for 48 h. The time study shows that enantioselectivity reached the maximum value of E = 244 after 72 h. Catalytic activity of these materials was hardly affected by 20 and 23% after five usages of enc-4 and enc-5, respectively.Öğe Improvement of catalytic activity of Candida rugosa lipase in the presence of calix[4]arene bearing iminodicarboxylic/phosphonic acid complexes modified iron oxide nanoparticles(ACADEMIC PRESS INC ELSEVIER SCIENCE, 2016) Ozyilmaz, Elif; Bayrakci, Mevlut; Yilmaz, MustafaIn the present study, iron oxide magnetite nanoparticles, prepared through a co-precipitation method, were coated with phosphonic acid or iminodicarboxylic acid derivatives of calix[4]arene to modulate their surfaces with different acidic groups. Candida rugosa lipase was then directly immobilized onto the modified nanoparticles through sol-gel encapsulation. The catalytic activities and enantioselectivities of the two encapsulated lipases in the hydrolysis reaction of (R/S)-naproxen methyl ester and (R/S)-2-phenoxypropionic acid methyl ester were assessed. The results showed that the activity and enantioselectivity of the lipase were improved when the lipase was encapsulated in the presence of calixarene-based additives; the encapsulated lipase with the phosphonic acid derivative of calix[4]arene had an excellent rate of enantioselectivity against the (R/S)-naproxen methyl and (R/S)-2-phenoxypropionic acid methyl esters, with E = 350 and 246, respectively, compared to the free enzyme. The encapsulated lipases (Fe-Calix-N(COOH)) and (Fe-Calix-P) showed good loading ability and little loss of enzyme activity, and the stability of the catalyst was very good; they only lost 6-11% of the enzyme's activity after five batches. (C) 2015 Elsevier Inc. All rights reserved.Öğe Improving catalytic hydrolysis reaction efficiency of sol-gel-encapsulated Candida rugosa lipase with magnetic beta-cyclodextrin nanoparticles(ELSEVIER SCIENCE BV, 2014) Ozyilmaz, Elif; Sayin, Serkan; Arslan, Mustafa; Yilmaz, MustafaA silica-based p-cyclodextrin was immobilized on magnetic nanoparticles to obtain a macrocyclic compound with magnetic property. Then, the beta-cyclodextrin-grafted magnetic nanoparticles were encapsulated with Candida rugosa lipase in sol-gel matrices using alkoxysilane precursors. The catalytic activity of the encapsulated lipases was evaluated with model reactions, i.e., the hydrolysis of p-nitro-phenylpalmitate (p-NPP) and the enantioselective hydrolysis of rasemic Naproxen methyl ester that was studied in an aqueous buffer solution/isooctane reaction system. The results indicate that the cyclodextrin-based, encapsulated lipase particularly exhibited high conversion and enantioselectivity behavior compared to the sol-gel free lipase. It was also observed that excellent enantioselectivity (E=399) was obtained for the encapsulated lipase with magnetic beta-cyclodextrin that has an ee value of S-Naproxen acid of about 98%. (C) 2013 Elsevier B.V. All rights reserved.Öğe A magnetically separable biocatalyst for resolution of racemic naproxen methyl ester(SPRINGER, 2013) Ozyilmaz, Elif; Sayin, SerkanCandida rugosa lipase (CRL) was encapsulated via the sol-gel method, using 5, 11, 17, 23-tetra-tert-butyl-25,27-bis(2-aminopyridine)carbonylmethoxy-26, 28-dihydroxy-calix[4]arene-grafted magnetic Fe3O4 nanoparticles (Calix-M-E). The catalytic activity of encapsulated lipase (Calix-M-E) was tested both in the hydrolysis of p-nitrophenyl palmitate (p-NPP) and the enantioselective hydrolysis of racemic naproxen methyl ester. The present study demonstrated that the calixarene-based compound has the potential to enhance both reaction rate and enantioselectivity of the lipase-catalyzed hydrolysis of racemic naproxen methyl ester. The encapsulated lipase (Calix-M-E) had great catalytic activity and enantioselectivity (E > 400), as well as remarkable reusability as compared to the encapsulated lipase without supports (E = 137) for S-Naproxen.Öğe Preparation of New Calix[4]arene-Immobilized Biopolymers for Enhancing Catalytic Properties of Candida rugosa Lipase by Sol-Gel Encapsulation(SPRINGER, 2013) Ozyilmaz, Elif; Sayin, SerkanThe article describes preparation of new calixarene biopolymers consisting of the immobilization of convenience calixarene derivative onto cellulose and chitosan biopolymers, and the encapsulation of these calixarene biopolymers with Candida rugosa lipase within a chemical inert sol-gel supported by polycondensation with tetraethoxysilane and octyltriethoxysilane. The catalytic properties of immobilized lipase were evaluated into model reactions employing the hydrolysis of p-nitrophenylpalmitate and the enantioselective hydrolysis of naproxen methyl esters from racemic prodrugs in aqueous buffer solution/isooctane reaction system. The resolution studies using sol-gel support have observed more improvement in the enantioselectivity of naproxen E = 300 with Cel-Calix-E than with encapsulated lipase without calixarene-based materials. Furthermore, the encapsulated lipase (Cel-Calix-E) was still retained about 39 % of their conversion ratios after the fifth reuse in the enantioselective reaction.Öğe Utilization of Catalytic Properties of the Encapsulated Lipase with Calix[4]arene-Adorned Sporopollenin(TAYLOR & FRANCIS LTD, 2018) Ozyilmaz, Elif; Sayin, SerkanThe dihydrazide calix[4]arene was immobilized onto sporopollenin in order to encapsulate Candida rugosa lipase (CRL) via sol-gel entrapment. The kinetic resolution of the new encapsulated lipase was investigated for enantioselective hydrolysis of racemic naproxen methyl ester and 2-phenoxypropionic acid methyl ester. The results demonstrated that the activity and enantioselectivity of the lipase were improved when the lipase was encapsulated in the presence of calix[4]arene-immobilized sporopollenin. The encapsulated lipase showed an excellent rate of enantioselectivity against the (R/S)-naproxen methyl and (R/S)-2-phenoxypropionic acid methyl esters, with E = 350 and 295, respectively, compared to the free enzyme.