Yazar "Güven, Reyhan Gül" seçeneğine göre listele

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    Cloning, purification and characterization of a thermostable β- galactosidase from Bacillus licheniformis strain KG9
    (Cellular and Molecular Biology Association, 2015) Bekler, Fatma Matpan; Stougaard, Peter; Güven, Kemal; Güven, Reyhan Gül; Acer, Ömer
    A thermo- and alkalitolerant Bacillus licheniformis KG9 isolated from Taslidere hot water spring in Batman/Turkey was found to produce a thermostable ?-galactosidase. Phylogenetic analysis showed that the 16S rRNA gene from B. licheniformis strain KG9 was 99.9% identical to that of the genome sequenced B. licheniformis strain DSM 13. Analysis of the B. licheniformis DSM 13 genomic sequence revealed four putative ?-galactosidase genes. PCR primers based on the genome sequence of strain DSM 13 were used to isolate the corresponding ?-galactosidase genes from B. licheniformis strain KG9. The calculated molecular weights of the ?-galactosidases I, II, III, and IV using sequencing data were 30, 79, 74, and 79 kDa, respectively. The genes were inserted into an expression vector and recombinant ?-galactosidase was produced in Escherichia coli. Of the four ?-galactosidase genes identified in strain KG9, three of them were expressed as active, intracellular enzymes in E. coli. One of the recombinant enzymes, ?-galactosidase III, was purified and characterized. Optimal temperature and pH was determined to be at 60 °C and pH 6.0, respectively. Km was determined to be 1.3 mM and 13.3 mM with oNPG (ortho-nitrophenyl-?-D-galactopyranoside) and lactose as substrates, respectively, and Vmax was measured to 1.96 ?mol/min and 1.55 ?mol/min with oNPG and lactose, respectively.
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    A highly inducible ?-galactosidase from enterobacter sp
    (Serbian Chemical Society, 2020) Shaikhan, Bestoon Ahmed; Güven, Kemal; Bekler, Fatma Matpan; Acer, Ömer; Güven, Reyhan Gül
    Enterobacter sp. 3TP2A isolated from a petroleum station was found to produce a novel, highly inducible mesophilic intracellular β-galactosidase in the presence of lactose up to 76.5 U mg-1. The enzyme was purified to 17.3-fold after gel permeation chromatography with a yield of approximately 11 %. The optimum pH and temperature values of the purified enzyme were found to be 8.0-9.0 and 35 °C, respectively. The molecular weight of the enzyme was approx. 60 kDa with a single band by both SDS-PAGE and native-PAGE, and estimated by gel filtration chromatography. The enzyme was inhibited by Zn2+ and EDTA, while Cu2+ had strong inhibitory effect even at low concentrations. Activation by Mg2+ and inhibition by EDTA show that the enzyme is metal-dependent or a metalloenzyme. The enzyme was slightly activated by 2-mercaptoethanol, while slightly inhibited by iodoacetamide. On the other hand, PCMB inhibited the enzymatic activity to a great extent, whereas it was completely inhibited by N-ethylmaleimide. The Vmax and Km values were calculated as 0.701 μmol min-1 and 0.104 mM, respectively. The results indicated that the β-galactosidase Enterobacter sp. 3TP2A might well be a good candidate for use in biotechnology, particularly in the area of environment and health.
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    Optimization of the thermostable alkaline and Ca-dependent ?-amylase production from Bacillus paralicheniformis by statistical modeling
    (Serbian Chemical Society, 2019) Bekler, Fatma Matpan; Yalaz, Seçi̇l; Güven, Reyhan Gül; Güven, Kemal
    A novel amylolytic enzyme producing thermoalkaliphilic bacterium, the source of industrially used enzymes was isolated. Isolated strain was identified by morphological, physio-biochemical tests and the 16S rRNA gene sequence analysis. The optimal conditions of enzyme activity were determined. For higher α-amylase production, the variables such as yeast extract, starch, CaCl2, (NH4)2SO4, NaCl and MgSO4 in the α-amylase production medium, the temperature and pH were screened by Plackett–Burman design and optimised using response surface methodology (RSM). The optimal conditions were found to be 0.15 g/L for starch, 0.15 mg/L for CaCl2 and 60 °C for temperature. By using RSM model, amylase production increase was achieved sevenfold. It is showed that this method can be utilised to optimize α-amylase production in athermophilic bacteria such as Bacillus paralicheniformis. Keywords: α-amylase; Bacillus paralicheniformis; optimization; response surface methodology.
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    Production, purification and characterisation of thermostable metallo-protease from newly isolated bacillus sp KG5
    (Foundation for Enviromental Protection and Research, 2015) Ahmetoğlu, Nazenin; Bekler, Fatma Matpan; Acer, Ömer; Güven, Reyhan Gül; Güven, Kemal
    Background: Due to the importance of microbial proteases in biotechnological applications, a number of microorganisms are being explored. The production, purification and characterisation of extracellular metallo-proteases by producing Bacillus sp. KG5 was studied. Material and Methods: Bacterial strain KG5 was isolated from Kös (Bingöl) hot spring. The strain KG5 was identified by morphological, physiological, biochemical and 16S rRNA gene sequencing. The effects of various parameters on protease production, such as time, temperature, pH, carbon and nitrogen sources and CaCl2were studied. The enzyme was purified by ammonium sulphate precipitation and Sephadex G-75 gel permeation chromatography. Molecular weight was calculated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and zymographic analysis. The effects of some metal ions, chelators and inhibitors on enzyme activity were determined. Results: The optimum temperature, pH and incubation period for protease production were 40-45°C, 7.0 and 24 h, respectively. It was determined that the best nitrogen sources were yeast extract and urea, while the best carbon sources were lactose and galactose. However, glucose as a source of carbon was found to inhibit the production of the enzyme. The maximum enzyme production was increased in the presence of CaCl2. The molecular weight of purified enzyme was found to be approximately 48 kDa. It was found that the enzyme was fully stable in the presence of 2 mM CaCl2 at 50°C after 120 min. Purified protease was significantly activated by Ca2+ and Mg2+, while it was greatly inhibited by Cu2+, Zn2+, Hg2+ and SDS as well as by the metal ion chelators ethylenediaminetetraacetic (EDTA) and 1,10-phenanthroline. Phenylmethylsulfonyl fluoride (PMSF) had a little effect on the enzyme. Conclusions: Our findings suggest the potential of this isolate for protease production and that this enzyme may be suitable for biotechnological applications.
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    Purification and characterization of polyphenol oxidase from purslane
    (Sociedade Brasileira de Ciencia e Tecnologia de Alimentos, SBCTA, 2017) Güven, Reyhan Gül; Güven, Kemal; Bekler, Fatma Matpan; Acer, Ömer; Alkan, Hüseyin; Doğru, Mehmet
    The polyphenol oxidase (PPO) is an enzyme that is responsible for the enzymatic browning of fruits and vegetables. This is generally undesired process and need to be prevented in food technology. PPO from purslane was purified, characterised and the kinetic parameters for three substrates namely, catechol, L-Dopa and 4-methylcatechol were determined. The optimum pH and temperature values were found to be pH 7.0 and 50 °C, respectively using the catechol as substrate. The apparent molecular weight of the PPO from purslane was determined as high as 163 kDa by partially denaturing SDS-PAGE. Moreover, the inhibition kinetics of the purified PPO were determined, using both synthetic and natural inhibitors. Among inhibitors tested, ascorbic acid was the most effective inhibitor with the lowest Ki value of 0.36 mM. This is the first study on the purification and characterisation of PPO from purslane (Portulaca oleracea) that may provide new insight into how to overcome the enzymatic browning.
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    Purification and characterization of thermostable and detergent-stable α-amylase from Anoxybacillus sp. AH1
    (University of Zagreb, 2016) Acer, Ömer; Bekler, Fatma Matpan; Pirinççioğlu, Hemşe; Güven, Reyhan Gül; Güven, Kemal
    A thermostable and detergent-stable ?-amylase from a newly isolated Anoxybacillus sp. AH1 was purified and characterized. Maximum enzyme production (1874.8 U/mL) was obtained at 24 h of incubation. The amylase was purified by using Sephadex G-75 gel filtration, after which an 18-fold increase in specific activity and a yield of 9 % were achieved. The molecular mass of the purified enzyme was estimated at 85 kDa by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). The optimum pH and temperature values of the enzyme were 7.0 and 60 °C, respectively. The enzyme was highly stable in the presence of 30 % glycerol, retaining 85 % of its original activity at 60 °C within 120 min. Km and vmax values were 0.102 ?mol and 0.929 ?mol/min, respectively, using Lineweaver- Burk plot. The enzyme activity was increased by various detergents, but it was significantly inhibited in the presence of urea. Mg2+ and Ca2+ also significantly activated ?-amylase, while Zn2+, Cu2+ and metal ion chelators ethylenediaminetetraacetic acid (EDTA) and 1,10-phenanthroline (phen) greatly inhibited the enzyme activity. ?-Amylase activity was enhanced by ?-mercaptoethanol (?-ME) and dithiothreitol (DTT) to a great extent, but inhibited by p-chloromercuribenzoic acid (PCMB). Iodoacetamide (IAA) and N-ethylmaleimide (NEM) had a slight, whereas phenylmethylsulfonyl fluoride (PMSF) had a strong inhibitory effect on the amylase activity.
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    Thermophilic and halophilic microorganisms isolated from extreme environments of Turkey, with potential biotechnological applications
    (Springer-Verlag Singapore Pte Ltd, 2018) Güven, Kemal; Bekler, Fatma Matpan; Güven, Reyhan Gül
    Turkey has a great number of different ecological areas, owning over 200 hot water resources and various hypersaline environments with a broad microbial diversity and opportunities for newly isolated microorganisms from extreme environments for many industrial applications. A variety of thermophilic and halophilic microorganisms in different regions of Turkey have been isolated and identified. The thermophilic bacterial members studied were Anoxybacillus, Geobacillus, Bacillus, Brevibacillus, and Aeribacillus belonging to the Bacillaceae family and the other thermophiles such as Thermus and Thermomonas, whereas the isolated halophilic microorganisms were mainly found to be members of the archaeal family Halobacteriaceae or grouped into bacterial phylum Bacteroidetes. In summary, the present study reviews on (1) isolating and identifying thermophiles and halophiles single or as community from various extreme habitats in Turkey based on conventional (morphological, physiological and biochemical tests) and/or molecular methods, (2) screening these extremophiles for industrially important enzymes, (3) studying other novel products and their use in other areas of biotechnology, and finally (4) discussing about the development strategies and the future perspectives on poorly studied extremophilic microorganisms in the country to fulfill future biotechnological and industrial demands.