Food Biochemistry and Food Processing (2 edition)

(Steven Felgate) #1

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
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