Immobilization of α‐amylase onto chitosan and its amino acid condensation adducts

Abstract

a-Amylase from Bacillus subtilis was immobilized on insoluble chitosan and its amino acid (L-glutamic acid and 4-aminobutyric acid) condensation adducts with the direct covalent attachment method and with glutaric dialdehyde (GDA) as a crosslinking agent. The immobilization process was carried out at 25 C and pH 6.9, and the maximum retained activity was obtained with 3 mg of a-amylase. The properties of the immobilized a-amylase were investigated and compared with those of the free aamylase. For the assays carried out via the crosslinking method at 25 C and pH 6.9, the retained activities were found to be 68.59, 97.36, and 79.50% for chitosan, chitosan-L-glutamic acid, and chitosan-4-aminobutyric acid crosslinked with 1% GDA, respectively. The immobilized a-amylase had better stability and higher retained activities with respect to the pH, temperature, and storage stability than the free a-amylase. In the repeated-use experiments, the a-amylase immobilized with chitosan-GDA (1%) retained about 46.45% of its original activity after 25 uses. In contrast, the activities of a-amylase immobilized on chitosan-L-glutamic acid-GDA (1%) and chitosan-4-aminobutyric acid-GDA (1%) did not change after 11 and 8 uses, respectively. The retained activities after 25 uses were 79 and 71% with respect to the original activity for the aforementioned carriers.

Synthesis and characterization of binary copolymers of methyl methacrylate with glycidyl methacrylate and 2‐hydroxy ethyl methacrylate as carriers for cellulase

“…The hydroxyl groups containing MMA-co-HEMA could be reacted with CMCT as a crosslinking agent, and then cellulase was bounded to it (crosslinking method). Scheme (6) shows the possible crosslinking mechanism between the MMA-co-HEMA support, CMCT (0.1%), and cellulase.…”

“…After these degrees, sharp degradation takes place till 337.29 C and 343.33 C (weight loss were 84.576% and 61.519 %), then gradual degradation takes place till 604. 6 C and 500 C (weight loss were 9.305% and 31.002%) for MMA-co-GMA and MMA-co-HEMA respectively, after these degrees complete decomposition occurs.…”

“…3,4 There are many methods, such as adsorption, crosslinking, covalent binding, etc., for enzyme immobilization. 5,6 The methods and supports employed for enzyme immobilization are chosen to ensure the highest retention of enzyme activity and its stability and durability. [7][8][9][10] Cellulases are enzymes that hydrolyze the b-(1-4) linkages in cellulose.…”

Formation of Functional Nanobiocatalysts with a Novel and Encouraging Immobilization Approach and Their Versatile Bioanalytical Applications

“…Although immobilzied α-amylase were highly stable against reaction temperature and some metal ions used as inhibitors, immobilization allows us to reperatedly use it and showed lower activitiy compared to its free form [20][21][22]. Moreover, in order to strengthen bonds between enzymes and the supports, the crosslinking agents played a crucial role to provide covalent attachment [2,[23][24][25][26][27][28][29][30][31][32][33][34][35][36].…”

Immobilization of Bacillus licheniformis α-amylase onto reactive polymer films

“…Alpha-amylase has been immobilized onto a wide variety of organic and inorganic supports, as for example silica gel (Saville et al, 2004), poly(ethylene terephtalate) fibers (Temocin and Yigitoglu, 2007), chitosan (El-Ghaffar and Hashem, 2009), and glass (Kahraman et al, 2007). It was demonstrated that the immobilization method and the physicochemical properties of the immobilization substrate play a fundamental role on the properties of the immobilized enzyme.…”