Food Biochemistry and Food Processing (2 edition)

BLBS102-c07 BLBS102-Simpson March 21, 2012 11:12 Trim: 276mm X 219mm Printer Name: Yet to Come

7 Biocatalysis, Enzyme Engineering and Biotechnology 151

Self-priming

PCR

(B) (C)

Figure 7.19.A schematic representation of the most frequently used methods for DNA shuffling.

entrapment or encapsulation (Podgornik and Tennikova 2002;

Fig. 7.20). These methods will be discussed in the following

sections.

Adsorption

Adsorption is the simplest method and involves reversible

interactions between the enzyme and the support material

(Fig. 7.20A). The driving force causing adsorption is usually

the formation of several non-covalent bonds such as salt links,

Table 7.8.Advantages of Immobilised Enzymes

1. Repetitive use of a single batch of enzymes.


2. Immobilisation can improve enzyme’s stability by
   restricting the unfolding of the protein.


3. Product is not contaminated with the enzyme. This is very
   important in the food and pharmaceutical industries.


4. The reaction is controlled rapidly by removing the enzyme
   from the reaction solution (or vice versa).

van der Waals, hydrophobic and hydrogen bonding (Calleri

et al. 2004). The methodology is easy to carry out and can be

applied to a wide range of support matrices such as alumina,

bentonite, cellulose, anion and cation exchange resins, glass,

hydroxyapatite, kaolinite, etc. The procedure consists of mixing

together the enzyme and a support under suitable conditions

of pH, ionic strength, temperature, etc. The most significant

advantages of this method are (i) absence of chemicals resulting

to a little damage to enzyme and (ii) reversibility, which allows

regeneration with fresh enzyme. The main disadvantage of the

method is the leakage of the enzyme from the support under

many conditions of changes in the pH, temperature and ionic

strength. Another disadvantage is the non-specific, adsorption

of other proteins or other substances to the support. This may

modify the properties of the support or of the immobilised

enzyme.

Covalent Coupling

The covalent coupling method is achieved by the formation

of a covalent bond between the enzyme and the support