BIOTECHNOLOGY - V. H. Herasymenko - 2006

Part II. Special Biotechnologies

Chapter 7. BIOTECHNOLOGY OF THE PRODUCTION AND APPLICATION OF IMMOBILIZED PREPARATIONS

7.4. SUPPORTS FOR ENZYME IMMOBILIZATION

7.4.4 Modification of the Support (Lat. mоdificatio — change)

To overcome certain undesirable properties or impart new ones, Supports are modified—meaning their properties are purposefully altered. Support modification involves treating them with substances that enhance their enzyme-binding capacity.

Numerous Methods exist for modifying matrices and activating their functional groups. For instance, the high solubility of silica supports can be overcome by modifying their Structure/108.html">Surface Properties, such as coating them with a film of aluminum, hafnium, titanium, etc. This reduces their solubility dozens of times over and eliminates non-specific sorption. One of the major drawbacks of spongy starch is its insufficient resistance to the action of Hydrolases. However, starch molecules treated with formaldehyde or glutaraldehyde undergo modification through cross-linking, rendering them resistant to hydrolases.

Surface modification of supports makes it possible to regulate their binding process with the Functional groups of the enzyme, while the resulting immobilized preparations exhibit enhanced stability.

The most widespread modifier is glutaraldehyde, which forms an amide bond between the amino group of the support and the carboxyl group of the enzyme. It is also referred to as a cross-linking agent (reagent).

To obtain immobilized Enzymes with predefined properties, activation of the modified support's surface is most frequently performed.

Support activation involves treating its surface with physical or chemical methods and agents to increase its binding capacity. This process generates electrophilic groups on the support surface (negative groups, e.g., COO^-) that exhibit high reactivity toward the nucleophilic groups of the protein (such as amino and sulfhydryl groups — NH₃⁺ and SH⁺).