3.3 Immobilization of Enzymes

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Biological processing techniques can be engaged in a variety of ways using enzymes

in the conversion of solid waste into a value-added products or forms of energy or

can be improved to the materials which provide fuels and energy.

3.3

Immobilization of Enzymes

Enzyme immobilization generally characterizes the integration of enzyme

molecules onto or into larger and non-active structures by several methods such as

covalent coupling, special encompassment, and physical adsorption. The immobi-

lization of enzymes provides several advantages such as easy parting from reaction

mixture, prevention of protein contamination into the product, enhanced stability,

repeated or continuous use, and possible modulation of catalytic property [4].

Immobilized enzymes can be reused in medical and analytical applications.

The reusability of biocatalyst reduces the production costs due to efficient process

control and recycling. Enzyme immobilization will help micro-devices in controlled

release of protein drugs. Immobilization also effectively helps in solid-phase

protein chemistry. During any biochemical reaction, the maintenance of structural

stability is highly challenging and this issue can be addressed by immobiliza-

tion. Immobilized enzymes provide higher functional efficiency and enhanced

reproducibility. The immobilized biocatalyst can be an enzyme or whole cell [5].

Enzyme immobilization procedures are developed with the objective of conversion

of biocatalysts into reaction catalysts. Enzyme immobilization is suitable and

a powerful tool to decrease the cost of production and or to develop the novel

industrial processes which are based on biotransformation. Approaches those

are carrier-bound or carrier-free offer novel alternatives for the extensive and

intensive use of enzymes. A unique example can be chitosan and its derivatives.

Several schemes have been developed to produce various varieties of the chemically

modified chitosan materials for the immobilization of enzymes.

3.3.1

Enzyme Immobilization Methods

Due to better turnover over a significant period of time, enzyme immobilization can

also provide an efficient increase in the ease of access of an enzyme to the substrate.

The present demand of world’s biotechnological industries is the development of

novel techniques to increase the shelf life and productivity of enzymes. Several vari-

eties of methods are practiced for an efficient enzyme immobilization.

3.3.1.1

Adsorption

Hydrophobic interactions and salt linkage result in an enzyme adsorption,

where enzyme can be either dried on the surface or physically adsorbed onto

the surface by immersion. Adsorbed enzymes can be shielded from several

physical problems such as proteolysis, aggregation, and the interactions with

hydrophobic interfaces. Silanized molecular sieves are successfully used as sup-

ports for enzyme adsorption due to the presence of silanols on the pore walls