3.3 Immobilization of Enzymes

37

Covalent bonding

Cross-linkage

Encapsulation

Entrapment

Adsorption

Enzyme

immobilization

techniques

Affinity

immobilization

Enzyme

Carrier/support

Figure 3.2

Diagrammatic representation of various enzyme immobilization methods.

[9]. Lipase entrapped in carrageenan showed high thermostability and tolerance

to organic solvent. Various enzyme immobilization methods were illustrated in

Figure 3.2.

3.3.2

Advantages of Immobilizing Enzymes

Advantages are described here, though they are mentioned earlier.

3.3.2.1

Stabilization

Immobilization need not to lead significant stabilization always. Both storage and

operational stability of the enzyme should be achieved by immobilization. The sta-

bility of correctly folded enzymes will be better than the corresponding unfolded

structure. Hence, enzymes are found to be more fragile catalysts than chemical cat-

alysts, and immobilization will make enzymes more robust.

3.3.2.2

Flexibility of Bioreactor Design

Enzyme immobilization allows one to choose among three fermentor designs,

packed bed, batch, and fluidized bed column reactor. Some of the most frequently

used carriers for the enzyme immobilization are porous micro-sized particles or

beads of dextran, cellulose, agarose, etc. The internal surface of beads is larger than

their outer surface. Large amount of enzyme can be immobilized on the surfaces

of beads, since enzyme dimensions are much smaller than that of the pores of the