Immobilized enzyme inhibitors

Enzyme catalysis Enzyme electrode Enzyme immobilization Enzyme immunoassay Enzyme inhibitors... 

Immobilized enzymes and cells, which are now known as immobilized biocatalysts, both provide us in general with the following advantages (1) continuous operation becomes practical (2) biocatalysts can be recovered and reused after reactions (3) biocatalysts can be formed into the shapes, such as membranes or beads, required for specific reaction processes (4) in some cases, the biocatalysts become stable with regard to changes in temperature, pH and inhibitor concentration. Immobilization methods can be classified according to the following scheme,... 

The Immobilized Enzyme System. The glucose isomerases used are immobilized and granulated to a particle size between 0.3 and 1.0 mm. The enzyme granulates must be rigid enough to withstand compaction when they are packed into the column. Ca2+ acts as an inhibitor in the system, and therefore calcium salts need to be removed from the feed syrup. Conversely, Mg2+ acts as an activator, and magnesium salts are added to the feed syrup. 

Fig. 10.7 Principle of affinity adsorption. The specific ligand (L), such as enzyme inhibitor and antigen, is immobilized on a water-insoluble carrier (C). A solute (S) can react selectively with the affinity ligand.

As demonstrated in a number of studies, the inhibitory activity of mucoadhesive polymers can be extensively improved by the immobilization of enzyme inhibitors onto the polymer without markedly influencing the mucoadhesive properties of the polymer. Such conjugates, comprising a mucoadhesive polymer and a covalently bound enzyme inhibitor exhibit diverse... 

Enzyme immobilization has been reported to improve the thermal stability of enzymes (1,2) and may also affect binding of substrates and inhibitors to the enzyme, thereby affecting the Michaelis constant and enzyme inhibition. Several previous studies have considered the advantages of immobilized enzymes with soluble substrates, and a few studies have also investigated the properties of immobilized enzymes with insoluble substrates. The main objective of the present work was to establish the effect of immobilization on the thermal stability of these enzymes, so that they may be used at elevated temperatures without significant activity loss. The immobilization conditions were varied, and their effect on the performance of the immobilized enzymes was analyzed with reference to their physiochemical and structural properties. 

These considerations are important in the context of analytical applications since they dictate the overall operational half-life of the immobilized system. In fact, an immobilized enzyme is particularly vulnerable to deactivation because it is unlikely to be used for monitoring a pure substance. Exposure to a physiological fluid or fermentor medium exposes the catalyst to inhibitors or extraneous matter. For example, the half-life of the immobilized lactase decreased from 89 days to 7 days when the substrate changed from 5% lactose solution to acid whey (40). 

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