Application of Enzymes

A PRACTICAL APPLICATION OF ENZYME INHIBITION BY A FALSE SUBSTRATE... 

In the following sections we will explain some applications of enzymes (and cells) in the transformation of sterols and steroids. You should realise, however, that for each process a decision has to be made whether to use an enzyme-mediated transformation or to use a chemical reaction. In many instances the biotransformation process is foe most attractive but, as we will see later, this is not always the case. 

Enzyme promiscuity is clearly advantageous to chemists since it broadens the applicability of enzymes in chemical synthesis. New catalytic activities in existing enzymes can be enhanced by protein engineering - appropriate mutagenesis of the enzymes [106]. Some of the most illustrative examples of this unusual activity of common enzymes are presented below. 

Table 25.3 Clinical uses and other applications of enzymes...

Enzyme-mediated syntheses of chiral non-racemic hetero-organic compounds, with a stereogenic centre located either on a heteroatom or on a carbon atom in a side chain, are comprehensively presented. Particular attention is paid to the use of common hydrolytic and reducing enzymes. On the basis of the results presented, some conclusions are drawn and proposals presented, which concern possible future direchons in the applications of enzymes to the synthesis and transformations of chiral hetero-organic derivatives. 

As described above, simple mutation, regardless of rational or random, sometimes changes the function of enzymes in a drastic manner. Especially, in the case of enzymes belonging to enolase superfamily, including decarboxylases, consideration of the reaction mechanism is important because the apparently different transformations proceed via a similar key intermediate. Thus, the well-designed mutation and structure of the substrates will lead to a successful expansion of the application of enzymes in organic synthesis. 

The application of enzymes has been discussed by Bollag (1992), and is not covered here. 

DeFrank 11 (1991) Organophosphorus cholinesterase inhibitors detoxification by microbial enzymes. In Applications of Enzyme Biotechnology (Ed IW Kelly and TO Baldwin), pp. 165-180. Plenum Press, New York. 

W. R. Moore, B. B. Beall, and S. A. Ali. Formation damage removal through the application of enzyme breaker technology. In Proceedings Volume, pages 135-141. SPE Formation Damage Contr Int Symp (Lafayette, LA, 2/14-2/15), 1996. 

TR. Dombrowski, E.M. Thurman, and G.B. Mohrman, A first application of enzyme-linked immunosorbent assay for screening cyclodiene insecticides in ground water, in Environmental Immunochemical Methods, ed. J.M. Van Emon, C.L. Ger-lach, and J.C. Johnson, American Chemical Society, Washington, DC, pp. 148-154 (1996). 

Enzymes have been proposed as a means of subtractive shrink-resist treatment. Their use has been discussed already in section 10.4-2. There are difficulties, however, in the commercially successful application of enzymes to wool at present. 

The application of enzymes for the mild hydrolysis of esters has been well established as a convenient method, and hence can be regarded as a standard methodology in organic synthesis. Accordingly, the expectation is met that such enzymatic ester cleavage reactions are included in domino processes. In this context, a number of publications describe enzyme-initiated fragmentation reactions. 

Eggleston, G. and Vercellotti, J.R. (eds) (2007) Industrial Applications of Enzymes on Carbohydrate-based Materials, ACS Symposium Series 6, Oxford University Press. 

One of the most promising applications of enzyme-immobilized mesoporous materials is as microscopic reactors. Galameau et al. investigated the effect of mesoporous silica structures and their surface natures on the activity of immobilized lipases [199]. Too hydrophilic (pure silica) or too hydrophobic (butyl-grafted silica) supports are not appropriate for the development of high activity for lipases. An adequate hydrophobic/hydrophilic balance of the support, such as a supported-micelle, provides the best route to enhance lipase activity. They also encapsulated the lipases in sponge mesoporous silicates, a new procedure based on the addition of a mixture of lecithin and amines to a sol-gel synthesis to provide pore-size control. 

Much activity is evident in the application of enzymes in synthetic and natural products chemistry (9-26). Surprisingly, this is not a new field of endeavor, but rather one that was extensively developed for application in solving synthetic chemical problems in the steroid field. The earliest work in this field took place during the early twentieth century, and serious industrial application of biocatalysis began in the late 1940s (8). The successes obtained in steroid chemistry clearly underlined the potential for biocatalysis to contribute in other areas of natural products chemistry including that with the alkaloids. 

The high specificity and stereoselectivity of enzymes, as well as the mild conditions under which they react, make enzyme-catalyzed reactions versatile tools in the synthesis of glycoconjugates. In some instances, an enzymic one-step transformation affords higher yields then the conventional and more-complex chemical synthesis. The application of enzymes in glycopeptide synthesis is under active development for selective deprotection and glycosylation purposes. 

Zajicek, J.L. Tillitt, D.E. Huckins, J.N. Petty, J.D. Potts, M.E. Nardone, D.A. 1996, Application of Enzyme-Linked Immunosorbent Assay (ELISA) for Measurement of Polychlorinated Biphenyls (PCBs) from Hydrophobic Solutions Extracts of Fish and Dialysates of Semipermeable Membrane Devices (SPMDs). In Environmental Immunochemical Methods, ACS Symposium Series 646 American Chemical Society Washington, D.C. Chapter 26, pp 307-325. 

Grdnqvist, S., Suumakki, A., Niku-Paavola, M.L., Kruus, K., Buchert, J. and Viikari, L. (2003). Lignocellulosic processing with oxidative enzymes. In Applications of Enzymes to Ugnocellulosics, Mansfield, D. and Saddler, J.N. (Eds.). ACS Symposium Series, 855, pp. 46-65. 

For some recent reviews on the use of enzymes in nonconventional media, see (a) Dreyer, S., Lembrecht, J., Schumacher, J. and Kragl, U., Enzyme catalysis in nonaqueous media past, present, and future in biocatalysis in the pharmaceutical and biotechnology industries, 2007, CRC Press, pp. 791-827 . (b) Torres, S. and Castro, G.R., Non-aqueous biocatalysis in homogeneous solvent systems. Food Technol. BiotechnoL, 2004, 42, 271-277 (c) Carrea, G. and Riva, S., Properties and synthetic applications of enzymes in organic solvent. Angew. Chem. Int. Ed., 2000, 39, 2226-2254. 

A major challenge in chemical and food industry is to perform oxidative and reductive conversions by biological means. In the application of enzymes for oxidative or reductive conversions a coenzyme like NAD(P)H or FADH2 is needed. For two... 

Further studies are necessary to define the field parameters which afford maximum activity of the enzyme (e.g., soil type, amount of moisture, whether or not multiple applications of enzyme are needed). 

Vellard M. The enzyme as drug application of enzymes as pharmaceuticals. Curr Opin Biotechnol 2003 14 444-50. 

Important for increasing the effectiveness of water-quality protection policies are the assessment of herbicides, nitrates, and antibiotics in water resources, the development of immunochemical techniques to measure herbicide residues, and the application of enzyme-linked immunosorbent assays. 

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