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    A New Design to Enhance the Enzyme Activities: Investigation of L-Asparaginase Catalytic Performance by IMAC Effect on g-C3N4 Nanolayers
    (Springer, 2024) Sert, Buse; Acet, Ömür; Noma, Samir Abbas Ali; Osman, Bilgen; Odabaşı, Mehmet; Ocakoğlu, Kasım
    Recently, graphite carbon nitride (g-C3N4) has come to the fore as a new material with its carbon-based two-dimensional structure, simple preparation procedure, and excellent physicochemical stability properties. This study aims to investigate the activity and kinetic studies of the L-asparaginase enzyme via immobilized metal ion affinity chromatography (IMAC) process of g-C3N4 nanolayers. Firstly, g-C3N4 nanolayers were synthetized and Ni2+ ions were binded their surfaces. The synthesized samples were investigated by SEM, ICP-MS, XRD, and FTIR. The highest L-ASNase adsorption on Ni2+-g-C3N4 nanostructures was 444.1 mg/g, at 3 mg/mL L-ASNase concentration. Optimal medium conditions for L-ASNase adsorption occurred at pH 8.0 and 25 °C. The immobilized enzyme showed improved stability relating to the soluble enzyme in extreme situations. On the other hand, the storage stability and reusability of the immobilized enzyme were found to be approximately 64 and 53% of the original activity after 29 days at room temperature and 10 cycles, respectively. From the Michaelis–Menten constants Km and Vmax, both of them decreased after immobilization compare to the free one. The obtained outcomes showed that the g-C3N4 is a suitable matrix for L-asparaginase immobilization with ideal catalytic efficiency and improved stability.
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    Öğe
    Comparative study of ASNase immobilization on tannic acid-modified magnetic Fe3O4/SBA-15 nanoparticles to enhance stability and reusability
    (Royal Society of Chemistry, 2020) Noma, Samir Abbas Ali; Ulu, Ahmet; Acet, Ömür; Sanz, Raúl; Sanz-Pérez, Eloy S.; Odabaşı, Mehmet; Ateş, Burhan
    In this work, l-asparaginase was immobilized on tannic acid-modified magnetic mesoporous particles. In brief, Fe3O4/SBA-15/tannic acid magnetic particles were synthesized, and their structures and morphologies were fully characterized using various methods. The properties of the free and immobilized enzyme were examined in terms of pH, temperature, thermal stability, storage stability, and reusability. Moreover, the effects of metal ions, inhibitors and organic solvents on the activity of the immobilized enzyme were investigated. Compared to the free enzyme, the immobilized enzyme possessed better tolerance to changes in ambient temperature and pH. Additionally, thermal incubation results showed that the free enzyme lost its activity, while the immobilized enzyme exhibited the opposite behavior. Most strikingly, the immobilized l-asparaginase exhibited a high degree of activity (70%) after being reused 16 times while also demonstrating 71% and 63% storage stability of the initial activity even after 28 days at 4 °C and room temperature, respectively. Together with these results, l-asparaginase was successfully immobilized upon Fe3O4/SBA-15/tannic acid magnetic nanoparticles with improved stability properties. This support holds great potential and opens up a novel perspective for growing applications.
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    L-asparaginase immobilized p(HEMA-GMA) cryogels: A recent study for biochemical, thermodynamic and kinetic parameters
    (Elsevier, 2021) Noma, Samir Abbas Ali; Acet, Ömür; Ulu, Ahmet; Önal, Burcu; Odabaşı, Mehmet; Ateş, Burhan
    Cryogels have recently been attracted intense attention as suitable carriers for enzyme immobilization. Herein, L-asparaginase was selected as the model enzyme due to its application such as pharmaceutical and food. Under optimum conditions, L-asparaginase was immobilized on poly (2-hydroxyethyl methacrylate-glycidyl methacrylate) cryogels with 68.8% of immobilization yield and 69.3% of activity recovery. The immobilized enzyme exhibited improved stability with respect to the soluble enzyme at extreme conditions, especially around acidic pH and high temperature. Also, the storage stability and reusability of the immobilized enzyme were found to be approximately 54% and 52% of the original activity after 28 days at room temperature and 10 cycles, respectively. The thermodynamic studies indicated that activation energy (E-a) of the free enzyme decreased from 13.08 to 10.97 kJ/mol, which means an increase in the thermostability of L-asparaginase. The Michaelis-Menten constants (K-m) of 2.04 and 1.67 mM, and the maximum reaction rates (V-max) of 170.0 and 115.0 mu M min(-1) were estimated for soluble and immobilized L-asparaginase, respectively. These findings demonstrated that the designed cryogels turn out to be a good carrier matrix for L-asparaginase immobilization with high catalytic efficiency and enhanced stability.
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    Synthesis, characterization and biological assessment of a novel hydrazone as potential anticancer agent and enzyme inhibitor
    (Elsevier B.V., 2020) Noma, Samir Abbas Ali; Erzengin, Mahmut; Tunç, Tuncay; Balcıoğlu, Sevgi
    In present work, a novel hydrazone compound, namely 1-(5-bromo-2,3-dimethoxybenzylidene)-2-(pyridine-2-yl) hydrazine (5Br2DM2PH), was synthesized by condensation reaction in acidic conditions. The structure of this compound was detailed elucidated by 1H NMR, FT-IR, UV/VIS and XRD methods. Antioxidant activity of the 5Br2DM2PH compound was investigated by scavenging activity on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals. The 5Br2DM2PH compound exhibited high scavenging activity compared with reference antioxidant. To determine in vitro cytotoxic effect of its, cell viability was tested using MTT assay on human breast (MCF-7) and colon (Caco-2) cancer cell lines. The results showed that the cytotoxic effect of the 5Br2DM2PH is more potent than cisplatin. The IC50 value for MCF-7 is 16.8 ?M while the value for Caco-2 is 11.8 ?M. In addition, the in vitro inhibitory property of the compound 5Br2DM2PH was carried out on human paraoxonase-1 (hPON-1) and the IC50 value was found as 13.8 ?g. Our ambitions for the novel 5Br2DM2PH compound will guide many future studies in the field of medicine, analytical and drug applications, as well as new organic synthesis.
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    Yeni hidrazon türevlerinin sentezlenmesi, radikal giderme aktivitelerinin ve insan serumundan saflaştırılan paraoksonaz-1 enzimi üzerine in vitro inhibisyon etkilerinin araştırılması
    (Aksaray Üniversitesi Fen Bilimleri Enstitüsü, 2016) Noma, Samir Abbas Ali; Erzengin, Mahmut
    Bu çalışmada, dört yeni hidrazon türevi sentezlenmiş ve yapıları X-Işını (XRD), Nükleer Manyetik Rezonans (H-NMR), Fourier Dönüşümlü Infrared Spektrofotometre (FTIR), Ultraviyole-Görünür spektrofotometre (UV-VIS) taramaları ve elementel analiz teknikleri ile aydınlatılmıştır. Tüm yeni sentezlenmiş bileşikler, 2,2-difenil-1-picrylhydrazyl (DPPH) yöntemiyle serbest radikal giderme aktiviteleri için taramaya tabi tutulmuştur. En düşük IC50 değerine (0,185 mg/mL) sahip B-2,4-MBPyH bileşiği, DPPH için en yüksek serbest radikal giderme aktivitesi göstermiştir. Paraoksonaz1 (PON1: EC 3.1.8.1) yüksek yoğunluklu lipoproteinlere (HDL) sıkıca bağlı, yapısında kalsiyum içeren bir metalo enzimdir ve memelilerde düşük yoğunluklu lipoproteinlerin (LDL) oksidasyonuna karşı koruyucu etkisi bulunmaktadır. Bu çalışmada, insan serum paraoksonaz1 (hPON1) enzimi, iki-aşamalı yöntem ile; amonyum sülfat çöktürmesi ve Sepharose-4B-L-tirozin-1-naftilamin hidrofobik etkileşim kromatografisi kullanılarak saflaştırılmıştır. Saflaştırılan enzimin SDS-poliakrilamid jel elektroforezinde, 43 kDa molekül ağırlığında tek bir band göstermiştir. Saflaştırılan enzim 21,22 U/mg spesifik aktiviteye sahiptir. Kullanılan yöntem ile % 17,484 verim ve 561,375 saflaştırma derecesine ulaşılmıştır. Ayrıca, paraokson substrat olarak kullanılarak, saflaştırılmış enzimin Km ve Vmax değerleri sırayla 0,018496 mM ve 114,96 U/mL olarak belirlenmiştir. Bu çalışmada, sentezlenen yeni bileşiklerin saflaştırılmış hPON1 üzerine in vitro inhibisyon etkileri de incelenmiştir. Sonuçlar, tüm hidrazin türevlerinin hPON1 enzim aktivitesini derişime bağlı olarak inhibe ettiğini göstermiştir. Çalışılan hidrazon türevleri arasında, en düşük IC50 değerine (0,0138 mg/mL) sahip B-2,3-MBPyH bileşiğinin hPON1 aktivitesi için en etkin inhibitör olduğu bulunmuştur. Bu çalışma, hPON1 aktivitesinin, çalışılan hidrazon türevlerine karşı oldukça yüksek derecede hassas olduğunu göstermiştir.