Enzymatic substrate engineering

Substrate engineering is rnie of the most promising techniques, which is applicable to all types of enzymatic transformations. As may be concluded from some of the foregoing examples, the ability of an enzyme to recognize the chirality of a given substrate predominantly depends on its steric shape. Electronic effects are involved but usually less important [278-281]. Thus, by variation of the substrate... 

Enzymatic reaction engineering (or optimization) is the systematic alteration of reaction components and/or conditions, such as solvent, additive, temperature, pH, enzyme formulation, substrate, etc., to access desired activity. Optimization can be performed in a linear fashion or using design of experiment (DOE) approaches [24]. In terms of the form of biocatalyst used, the main options are... 

One of the major challenges associated with enzyme-catalyzed phenol removal is the prohibitive cost of the enzyme resulting from inactivation processes that occur during treatment [24], Enzymes are not only susceptible to inactivation by contaminants that are not directly involved in the catalytic reaction, but rather, they can also be inactivated, or at least inhibited, by some substrates and products of the catalytic reaction. Because such mechanisms can strongly influence the economics of enzymatic processes, they must be studied in reasonable detail. From such knowledge, engineering approaches can be found to minimize the occurrence of inactivation mechanisms. 

Fan, L. T., Lee, Y. H., and Beardmond, D. H. 1980. Major chemical and physical features of cellulosic materials as substrates for enzymatic hydrolysis. In Fiechter, A. (Ed.), Advances in Biochemical Engineering. New York Springer-Verlag. 

In principle, several routes exist for enzymatic isomaltose synthesis. With respect to cost-effectiveness it is obvious that one should use substrates like sucrose or starch that can be exploited by dextransucrase (EC 2.4.1.5) or glucoamylase (EC 3.2.1.3), respectively. However, in both cases, isomaltose represents a side product which is released only in small proportions next to dextran or glucose as main products. Realization of higher yields requires extensive time and effort with respect to engineering of reaction and catalyst design. Based on kinetic investigations dextransucrase has been chosen for the production of isomaltose with sucrose as the substrate, and glucose as an acceptor (see Sect. 2.1). 

In terms of achievements, selection from libraries of phage-displayed enzymes has afforded several enzymes with modified specificities and several abzymes. A combination of in vivo selection and in vitro selection for binding to ligands unrelated to the substrates has also opened the way to the engineering of the regulation of enzymatic activity. 

Hydrophilicity is an important criterion for the use of synthetic polymers. Existing methods for surface modihcation of synthetic hbers are costly and complex. Therefore, the enzymatic surface modihcation of synthetic hbers is a new and green approach to synthesize polymers with improved surface properties. Use of enzymes for surface modihcation of polymers will not only minimize the use of hazardous chemicals but also minimize the environment pollution load. Besides these, the enzyme-modihed polymers can also immobilize those enzymes which can only bind to the selective functional groups present on the polymeric surface such as —COOH and —NH2. Similarly, substrates can immobilize on the solid matrix (or polymer), which will be easily accessible to the enzymes. Genetic engineering can be employed for the modihcation of active sites of enzymes for better polymer catalysis. 

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