Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Immobilization of Thermophilic Esterase on Magnetic Cornstarch Nanoparticles for Biological Applications(Izmir Institute of Technology, 2016) Öz, Yasin; Şanlı Mohamed, GülşahIn last three decades, even the role of enzymes for biological and industrial applications has become more worthy, enzymes also have some defects. The enzyme immobilization allows to overcome these defects by improving abilities of reusing of catalysts by multiple times, easier reactor operation and product separation. Due to its potential use in biological and industrial applications, isolated thermophilic esterase from Geobacillus sp. was immobilized on magnetic cornstarch nanoparticles. In order to determine activity performance of immobilized enzyme, the effects of temperature, pH and some chemicals on enzyme activity were investigated. The results have shown that after immobilization, the relative activity of immobilized esterase has increased to 80% at 80 0C in comparison to free esterase. Therewithal, the reusability of immobilized esterase has increased fourfold in comparison to free esterase. The magnetic character of the support media has brought ease to separate biocatalysts from reaction media.Master Thesis Purification and Biochemical Characterization of Xylanase Expressed in Thermophilic Geobacillus Sp.(Izmir Institute of Technology, 2015) Algan, Müge; Köksal, Mustafa; Şanlı Mohamed, Gülşah; Şanlı Mohamed, Gülşah; Köksal, MustafaXylanase is an enzyme that catalyzes the degradation of the linear polysaccharide β-1,4-xylan into xylose and breaks down the hemicellulose structure of plant cell wall. The xylanolytic property of the enzyme makes it preferable for many biotechnological applications in industry. This enzyme is possibly produced by some bacterial and fungal microorganisms. In this study, briefly, xylanase enzyme was expressed in thermophillic Geobacillus sp. and purified by cold acetone precipitation and gel filtration chromatography. Molecular weight of our xylanase was found as 40.1 kDa by SDS-PAGE and this protein band was verified by Native-PAGE activity staining. Finally, it was characterized using biochemical methods. For characterization studies, Km and Vmax values were calculated from Lineweaver-Burk plot as 10.2 mg/ml and 31.7 U/ml, respectively. The optima temperature and pH for enzyme activity were investigated using beechwood xylan as substrate and found as 55°C and 8.0, respectively. Furthermore, effects of some metal ions, various chemical reagents and organic solvents on enzyme activity were also determined and we observed that Ca2+, Mn2+ and Co2+ affected the activity positively while Zn2+, Cd2+, Fe3+, EDTA, SDS, CHAPS and DTT shielded the activity. And only β-mercaptoethanol caused a significant change amoung organic solvents. Lastly, that the enzyme has a long shelf-life was confirmed assaying the samples taken from enzyme stocks stored at +4°C and room temperature for six weeks.