Modification and characterization of cellulosic cotton fibers for efficient immobilization of urease

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• 作者：M. Monier ; ^{monierchem@yahoo.com} ; A.M.A. El-Sokkary
• 关键词：Cotton ; Grafting ; Urease ; Acrylonitrile
• 刊名：International Journal of Biological Macromolecules
• 出版年：2012
• 期刊代码：62_01418130
• 类别：abs
• 出版时间：July-August, 2012
• 卷：51
• 期：1-2
• 页码：18-24
• 文件大小：634 K

摘要

Cotton fibers were first grafted by polyacrylonitril in the presence of KMnO₄ and oxalic acid as a combined redox initiator. Moreover, modification of the grafted cotton fibers was done by changing the nitrile group (CN) into hydrazidine group through the reaction with hydrazine hydrate, then the fibers were activated by glutaraldehyde to introduce free aldehyde groups which were able to react with amino groups of urease to form Schiff's base, and result in cotton fibers immobilized urease. The efficiency of the immobilization was evaluated by examining the relative enzymatic activity of enzyme before and after the immobilization of urease. The results showed that the optimum temperature of immobilized urease was 35 掳C, which was higher than that of the free enzyme (30 掳C), and the immobilized urease exhibited a higher relative activity than that of free urease over 35 掳C. The optimal pH for immobilized urease was 6.5, which was lower than that of the free urease (pH 7.0), and the immobilization resulted in stabilization of enzyme over a wider pH range. The kinetic constant value (K_m) of immobilized urease was higher than that of the free urease. However, the thermal and operational stabilities of immobilized urease have been improved greatly.