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Document Type |
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Thesis |
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Document Title |
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Immobilization of different enzymes on magnetic nanoparticles تحميل إنزيمات مختلفة على جسيمات نانوية مغناطيسية |
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Subject |
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Faculty of Sciences |
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Document Language |
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Arabic |
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Abstract |
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Firstly, horseradish peroxidase (HRP) was immobilized on non-modified Fe3O4 magnetic nanoparticles. Immobilized HRP was characterized by FT-IR spectroscopy, scanning electron microscopy and energy dispersive X-ray. The immobilized HRP retained 55% of its initial activity after ten reuses. The pH was shifted from 7.0 for soluble HRP to 7.5 for the immobilized HRP. The optimal temperature of soluble HRP was shifted from 40°C to 50°C for the immobilized HRP. The immobilized HRP is more thermal stable than soluble HRP. Various substrates were oxidized by immobilized HRP with higher efficiency than that of soluble HRP. Km values of the soluble HRP and the immobilized HRP were 31 and 45 mM for guaiacol and 5.0 and 7.0 mM for H2O2, respectively. Some tested metals had shown less inhibitory effect on immobilized HRP compared with soluble HRP. The immobilized HRP was more stable against high concentration of urea, Triton X-100 and isopropanol. The immobilized HRP was found to exhibit high resistance to proteolysis by trypsin than soluble enzyme.
Secondly, a new enzyme carrier had been developed using covalent immobilization of α-amylase from Trichoderma harzianun onto modified magnetic Fe3O4-nanoparticles. The effect of polypyrrole/silver nanocomposite (PPyAgNp) percentage on weight of Fe3O4 and pH on the immobilization of α-amylase was studied. The maximum immobilization efficiency (75 %) was detected at 10 % PPyAgNp/Fe3O4-nanocomposite and pH 7.0. Immobilization of α-amylase on 10 % PPyAgNp/Fe3O4-nanocomposite was characterized by FT-IR spectroscopy and scanning electron microscopy. The reuse capability of immobilized α-amylase was 80% of its initial activity after 10 runs. Immobilized α-amylase was found to be stable against both physical and chemical properties with regard to pH, temperature and metal ions. The immobilized α-amylase hydrolyzed substrate analogs such as starch, glycogen, amylopectin, amylose, α-cyclodextrine and β-cyclodextrin with high efficiency than that of soluble α-amylase. The affinity of immobilized α-amylase towerds starch was higher compared with soluble enzyme, where Km values of the soluble α-amylase and the immobilized α-amylase were 3.5 mg and 2.5 mg of starch, respectively. In conclusion, the physical immobilization of peroxidase and α-amylase on iron magnetic nanoparticles improved the enzyme stability toward the denaturation induced by pH, heat, metal ions, urea, detergent and water–miscible organic solvent. The immobilization of these enzymes on magnetic nanoparticles could be successfully used in bioremediation, food and other medical applications. |
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Supervisor |
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Prof. Saleh Ahmed Mohamed |
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Thesis Type |
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Doctorate Thesis |
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Publishing Year |
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1438 AH
2017 AD |
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Co-Supervisor |
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Prof. Ibrahim Hassan Ibrahim |
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Added Date |
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Wednesday, May 17, 2017 |
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Researchers
| ماجد حمد الحربى | AlHarbi, Majed Hamd | Researcher | Doctorate | |
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