enzyme immobilization
Enzyme Immobilization Methods
Covalent Binding:
Covalent binding is a conventional method for immobilization; it can be achieved by direct attachment with the enzyme and the material through the covalent linkage [37]. The covalent linkage is strong and stable and the support material of enzymes includes polyacrylamide, porous glass, agarose and porous silica [38]. Covalent method of immobilization is mainly used when a reaction process does not require enzyme in the product, this is the criteria to choose covalent immobilization method. This covalent binding of the enzyme with the support material involves two main steps such as, the activation of the support material by the addition of the reactive compound and the second one is the modification of the polymer backbone to activate the matrix (Figure 1). The activation step produces the electrophilic group on the support material, so that the support material couples /reacts with the strong nucleophiles on the proteins [2]. For example glutaraldehyde is the activation method, in this reaction the amine group reacts with the activated matrix [39]. The covalent binding is normally formed between the functional group in the support matrix and the enzyme surface that contains the amino acid residues. The amino acid residues involved in the covalent binding are the sulfhydryl group of cysteine, hydroxyl group of serine and threonine [40, 41]. The attachment between the enzyme and the support material can be achieved either through direct linkage or through the spacer arm. The potentiality of using the spacer arm is that it provides the greater degree of the mobility to the enzymes hence the enzymes show the higher activity when compared to the direct attachment.
Entrapment:
Enzymes are occluded in the synthetic or natural polymeric networks, it is a permeable membrane which allows the substrates and the products to pass, but it retains the enzyme inside the network, the entrapment can be achieved by the gel, fibre
Covalent Binding:
Covalent binding is a conventional method for immobilization; it can be achieved by direct attachment with the enzyme and the material through the covalent linkage [37]. The covalent linkage is strong and stable and the support material of enzymes includes polyacrylamide, porous glass, agarose and porous silica [38]. Covalent method of immobilization is mainly used when a reaction process does not require enzyme in the product, this is the criteria to choose covalent immobilization method. This covalent binding of the enzyme with the support material involves two main steps such as, the activation of the support material by the addition of the reactive compound and the second one is the modification of the polymer backbone to activate the matrix (Figure 1). The activation step produces the electrophilic group on the support material, so that the support material couples /reacts with the strong nucleophiles on the proteins [2]. For example glutaraldehyde is the activation method, in this reaction the amine group reacts with the activated matrix [39]. The covalent binding is normally formed between the functional group in the support matrix and the enzyme surface that contains the amino acid residues. The amino acid residues involved in the covalent binding are the sulfhydryl group of cysteine, hydroxyl group of serine and threonine [40, 41]. The attachment between the enzyme and the support material can be achieved either through direct linkage or through the spacer arm. The potentiality of using the spacer arm is that it provides the greater degree of the mobility to the enzymes hence the enzymes show the higher activity when compared to the direct attachment.
Entrapment:
Enzymes are occluded in the synthetic or natural polymeric networks, it is a permeable membrane which allows the substrates and the products to pass, but it retains the enzyme inside the network, the entrapment can be achieved by the gel, fibre