الفهرس 
Aim of the workOnly 14 pages are availabe for public view
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Abstract
In the present study three enzymes were immobilized, namely ADA Adenosine Deaminase, Pullulanase and 13-Amylase. The immobilization of these enzymes was carried out onto three different polymeric materials: agarose, casein and butylacrylate/ acrylic acid (BuAI AAc) copolymer. The factors affecting the amount of enzyme attachment onto the polymeric supports such as incubation pH, enzyme concentration and incubation time was investigated. The maximum amount of enzyme immobilized onto the different polymeric supports occurred at incubation pH values of 7.5, 5 and 7 for Adenosine Deaminase (cone. 42 units/ gm), Pullulanase (cone. 16 units/gm) and P-amylase (86 units/ gm), respectively. The incubation time needed for the three enzymes was found to be 8, 10 and ll hours, respectively.
Some physico-<:hemical properties of the free and immobilized enzymes such as reuse efficiency, optimum temperature and thermal stability, pH optimum and stability, storage stability and the effect of y-radiation were studied. For the immobilization process, chemical and radiation methods were used. The reuse efficiency of the free and immobilized enzymes showed that the enzymes immobilized by a crosslinking technique using gultaric dialdehyde (GA) showed poor durability and the relative activity decreased sharply due to the leakage after repeated washing, while the enzymes immobilized by covalent bonds to the carriers showed in most cases a slight decrease in relative activity (around 20%) after being used l 0 times. Temperature optimum and thermal inactivation as well as pH optimum and stability showed a severe loss in the activity of the free enzymes, while the temperature and pH profiles of the immobilized enzymes was much broader at higher temperatures demonstrating the effectiveness of the carriers protecting the enzymes. Storage of the free and immobilized enzymes at 4°C in the dry and wet states for 4-6 months, showed that the free enzyme lost most of its activity after storage. The storage of the immobilized enzymes in the dry state was much better than in the wet state, which may be due to the prevention of autodigestion and thermal denaturation. Storage at room temperature (25°C) showed much less stability of the immobilized enzyme. Subjecting the immobilized enzymes to doses of y-radiation 0.5-10 Mrad showed complete loss in the activity of the free enzyme at a dose of 5 Mrad, while the immobilized enzymes showed relatively high resistance to y-radiation up to a dose of
5 Mrad. Also, Nuclear Magnetic Resonance CH-NMR), FTIR, DSC measurement
were carried out to confirm the structure and the immobilization process of the enzymes onto the polymeric carriers.