They are intimately involved in numerous biotechnological processes, such as cheese making, beer brewing and winemaking, that date back to the dawn of civilization.
Examples include food (baking, dairy products, starch conversion) and beverage (beer, wine, fruit and vegetable juices) processing, animal feed, textiles, pulp and paper, detergents, biosensors, cosmetics, health care and nutrition, waste water treatment, pharmaceutical and chemical manufacture and, more recently, biofuels such as biodiesel.
In the production of fine chemicals, flavors and fragrances, agrochemicals and pharmaceuticals an important benefit of enzymes is the high degree of chemoselectivity, regioselectivity and enantioselectivity which they exhibit.
Notwithstanding all these desirable characteristic features of enzymes, their widespread industrial application is often hampered by their lack of long term operational stability and shelf-storage life, as well as by their cumbersome recovery and re-use.
Immobilization also facilitates the efficient recovery and re-use of costly enzymes, in many applications a conditio sine qua non for economic viability, and enables their use in continuous, fixed-bed operation.
Enzymes are rather delicate molecules that can easily lose their unique three-dimensional structure, essential for their activity, by denaturation (unfolding).
The use of a carrier inevitably leads to ‘dilution of activity’, owing to the introduction of a large portion of non-catalytic ballast, ranging from 90% to >99%, which results in lower space-time yields and productivities.
CLECs proved to be significantly more stable to denaturation by heat, organic solvents and proteolysis than the corresponding soluble enzyme or lyophilized (freeze-dried) powder.
Their operational stability and ease of recycling, coupled with their high catalyst and volumetric productivities, renders them ideally suited for industrial biotransformations.
It could be used, for example, for the direct isolation of an enzyme, in a purified and immobilized form suitable for performing biotransformations, from a crude fermentation broth.