Enzyme immobilization

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5. Inorganic Carriers Organic Natural Carriers Organic Synthetic Carriers
• High pressure stability
• May undergo abrasion
Examples:
• Commercially SiO2
available materials-
• Porous Glass
• Silica
• Cordierite
• Silica gel
• Favorable compatibility
with proteins.
Examples:
• Cellulose derivatives-
• DEAE-cellulose
• CM-cellulose
• Dextran
• Polysaccharides
• Agarose
• Starch
• Pectin
• Chitosan
• High chemical and
mechanical stability
Examples:
• Polystyrene
• Polyvinyl acetate
• Acrylic polymers

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ADVANTAGES DISADVANTAGES
Simple and economical Relatively low surface area for binding
Limited loss of activity Exposure of enzyme to microbial attack
Can be recycled, regenerated & reused Yield are often low due to inactivation and
desoption

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ADVANTAGES DISADVANTAGES
No chemical modification The enzyme may leak from the pores
Relatively stable forms
Easy handling and reusage

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ADVANTAGES DISADVANTAGES
The binding force between enzyme and carrier
is so strong that no leakage of the enzyme
occurs, even in the presence of substrate or
solution of high ionic strength.
Covalent binding may alter the conformational
structure and active center of the enzyme,
resulting in major loss of activity and/or
changes of the substrate.

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ADVANTAGES DISADVANTAGES
Very little desorption (enzyme strongly bound) Cross linking may cause significant changes in
the active site.
Higher stability (pH, ionic & substrate
concentration)
Not cost effective

13. CHARACTERISTICS ADSORPTION COVALENT
BINDING
ENTRAPMENT MEMBRANE
CONFINEMEN
Preparation Simple Difficult Difficult Simple
Cost Low High Moderate High
Binding force Variable Strong Weak Strong
Enzyme leakage Yes No Yes No
Applicability Wide Selective Wide Very Wide
Running Problems High Low High High
Matrix effects Yes Yes Yes No
Large diffusional barriers No No Yes Yes
Microbial protection No No Yes Yes

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