Enzymatic catalysis application

Hie ester linkage of aliphatic and aliphatic-aromatic copolyesters can easily be cleaved by hydrolysis under alkaline, acid, or enzymatic catalysis. This feature makes polyesters very attractive for two related, but quite different, applications (i) bioresorbable, bioabsorbable, or bioerodible polymers and (ii) environmentally degradable and recyclable polymers. 

Enhanced thermal stability enlarges the areas of application of protein films. In particular it might be possible to improve the yield of reactors in biotechnological processes based on enzymatic catalysis, by increasing the temperature of the reaction and using enzymes deposited by the LB technique. Nevertheless, a major technical difficulty is that enzyme films must be deposited on suitable supports, such as small spheres, in order to increase the number of enzyme molecules involved in the process, thus providing a better performance of the reactor. An increased surface-to-volume ratio in the case of spheres will increase the number of enzyme molecules in a fixed reactor volume. Moreover, since the major part of known enzymatic reactions is carried out in liquid phase, protein molecules must be attached chemically to the sphere surface in order to prevent their detachment during operation. 

Dordick, J.S. (July 1991) Enzymatic catalysis in organic media Fundamentals and selected applications. ASGSBBull. 4(2), 125-132. 

An ionic liquid can be used as a pure solvent or as a co-solvent. An enzyme-ionic liquid system can be operated in a single phase or in multiple phases. Although most research has focused on enzymatic catalysis in ionic liquids, application to whole cell systems has also been reported (272). Besides searches for an alternative non-volatile and polar media with reduced water and orgamc solvents for biocatalysis, significant attention has been paid to the dispersion of enzymes and microorganisms in ionic liquids so that repeated use of the expensive biocatalysts can be realized. Another incentive for biocatalysis in ionic liquid media is to take advantage of the tunability of the solvent properties of the ionic liquids to achieve improved catalytic performance. Because biocatalysts are applied predominantly at lower temperatures (occasionally exceeding 100°C), thermal stability limitations of ionic liquids are typically not a concern. Instead, the solvent properties are most critical to the performance of biocatalysts. 

Computational QM/MM studies presented thus far provide better understanding of enzymatic catalysis and description of interactions within the active sites. Comparison of experimentally determined isotope effects with corresponding values predicted theoretically serves to indicate that theoretical methods yield meaningful results. In the remaining part of this contribution we will show how information about properties of the transitions state gathered collectively from molecular modeling and measurements of kinetic isotope effects can be effectively used in devising new compounds with therapeutic applications. 

Esters of fatty acids with monohydric alcohols find applications as emollients in cosmetics. They are prepared by acid- or base-catalyzed (trans)esterifications [200, 205]. As with biodiesel production, the use of enzymatic catalysis offers potential benefits but in the case of these specialty fatty acid esters there is a special advantage the products can be labelled as natural. Consequently, they command a higher price in personal care products where natural is an important customer-perceived advantage. Examples include the synthesis of isopropylmy-ristate by CaLB-catalyzed esterification [206] and n-hexyl laurate by Rhizomucor miehei lipase (Lipozyme IM-77)-catalyzed esterification [207] (see Fig. 8.38). 

The effects of macromolecules other than surfactants on the rates of organic reactions have been investigated extensively (Morawetz, 1965). In many cases, substrate specificity, bifunctional catalysis, competitive inhibition, and saturation (Michaelis-Menten) kinetics have been observed, and therefore these systems also serve as models for enzyme-catalyzed reactions and, in these and other respects, resemble micellar systems. Indeed, in some macromolecular systems micelle formation is very probable or is known to occur, and in others mixed micellar systems are likely. Recent books and reviews should be consulted for a more detailed description of macromolecular systems and for their applicability as models for enzymatic catalysis and other complex interactions (Morawetz, 1965 Bruice and Benkovic, 1966 Davydova et al., 1968 Winsor, 1968 Jencks, 1969 Overberger and Salamone, 1969). 

Abstract Recent progresses in molecularly imprinted metal-complex catalysts are highlighted in this chapter. Molecular imprinting is a technique to produce a cavity with a similar shape to a particular molecule (template), and the molecularly imprinted cavity acts as shape-selective reaction space for the particular reactant. The application of the molecular-imprinting technique to heterogeneous metal-complex catalysts is focused in the viewpoint of a novel approach in the design of shape-selective catalysis mimicking enzymatic catalysis. 

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