Acrylamide grafted poly(ethylene terephthalate) fibers activated by glutaraldehyde as support for urease |
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Authors: | Y Murat Elçin Mehmet Saçak |
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Institution: | (1) Department of Chemistry, Faculty of Science Ankara University, 06100 Ankara, Turkey |
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Abstract: | Urease was covalently immobilized on acrylamide-grafted poly (ethylene terephthalate) fibers after glutaraldehyde activation.
Ureasecontaining fibers showed a very high operational stability and reusability, with about 85% of the initial activity after
90 d. The thermostability of the bound urease was positively influenced, and a slight change in optimum temperature was observed
after immobilization, when compared with the free enzyme. The pH optimum of both types of urease was found to be the same,
but immobilized urease showed an increased stability in a broader range of pH. The kinetic studies exhibited a slightly higherK
m
value for the bound enzyme, with a value of 4.50 mmol dm-3, when compared with the free enzyme (2.82 mmol dm-3), which demonstrated that the immobilization procedure did not cause an unfavorable conformation for the substrate-product
formation and a hindered diffusion. The graft yield was also found effective on maximum activity of immobilized urease. Twenty-five
percent of the acrylamide-grafted fibers exhibited the highest enzymatic activity together with the highest water uptake.
Higher graft yields were not suitable for the immobilization of the enzyme molecules as a result of crosslinks formed between
the poly(acrylamide) chains and glutaraldehyde. |
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Keywords: | Urease immobilization poly(ethylene terephthal-ate) fibers graft polymerization acrylamide grafting glutaraldehyde activation urea hydrolysis |
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