Comparison of Free and Immobilized L-asparaginase Synthesized by Gamma-Irradiated Penicillium cyclopium
| Autor: | Saadia M. Easa, Eman Araby, Abdel-Monem H. El-Refai, Fawkia M. El-Beih, Heba A. El-Refai, Mona S Shafei, Sanaa K Gomaa, Hanan Mostafa |
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| Rok vydání: | 2016 |
| Předmět: |
0301 basic medicine
Microbiology (medical) Asparaginase Immobilized enzyme Penicillium cyclopium Amberlite IR-120 Amberlite Applied Microbiology and Biotechnology Microbiology Gene Expression Regulation Enzymologic 03 medical and health sciences chemistry.chemical_compound Gene Expression Regulation Fungal Acetone chemistry.chemical_classification biology Penicillium ionic binding immobilization General Medicine Hydrogen-Ion Concentration biology.organism_classification Enzymes Immobilized L-asparaginase gamma irradiation Enzyme assay Kinetics 030104 developmental biology Enzyme chemistry Metals Mutation biology.protein Specific activity Nuclear chemistry |
| Zdroj: | Polish journal of microbiology. 65(1) |
| ISSN: | 1733-1331 |
| Popis: | Gamma irradiation is used on Penicillium cyclopium in order to obtain mutant cells of high L-asparaginase productivity. Using gamma irradiation dose of 4 KGy, P. cyclopium cells yielded L-asparaginase with extracellular enzyme activity of 210.8 ± 3 U/ml, and specific activity of 752.5 ± 1.5 U/mg protein, which are 1.75 and 1.53 times, respectively, the activity of the wild strain. The enzyme was partially purified by 40–60% acetone precipitation. L-asparaginase was immobilized onto Amberlite IR-120 by ionic binding. Both free and immobilized enzymes exhibited maximum activity at pH 8 and 40°C. The immobilization process improved the enzyme thermal stability significantly. The immobilized enzyme remained 100% active at temperatures up to 60°C, while the free asparaginase was less tolerant to high temperatures. The immobilized enzyme was more stable at pH 9.0 for 50 min, retaining 70% of its relative activity. The maximum reaction rate (Vmax) and Michaelis-Menten constant (Km) of the free form were significantly changed after immobilization. The Km value for immobilized L-asparaginase was about 1.3 times higher than that of free enzyme. The ions K+, Ba2+ and Na+ showed stimulatory effect on enzyme activity with percentages of 110%, 109% and 106% respectively. |
| Databáze: | OpenAIRE |
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