Enzyme commercial applications

Many of these have been demonstrated with a range of antibiotics and antibiotic precursors, although relatively few have been applied commercially. We have included a list of published examples in the form of an Appendix at the end of this chapter. We do not expect you to remember the details of this Appendix. It has been included as an potential for illustration of the potential to use enzymes to modify organic molecules like antibiotics. Usin9 It should be anticipated that, as enzyme technology develops and the search for new enzymes antibiotics continues, an increasing number of enzyme-based transformation will find commercial application. 

Many procedures have been suggested to achieve efficient cofactor recycling, including enzymatic and non-enzymatic methods. However, the practical problems associated with the commercial application of coenzyme dependent biocatalysts have not yet been generally solved. Figure A8.18 illustrates the continuous production of L-amino adds in a multi-enzyme-membrane-reactor, where the enzymes together with NAD covalently bound to water soluble polyethylene glycol 20,000 (PEG-20,000-NAD) are retained by means of an ultrafiltration membrane. 

In many cases, the racemization of a substrate required for DKR is difficult As an example, the production of optically pure cc-amino acids, which are used as intermediates for pharmaceuticals, cosmetics, and as chiral synfhons in organic chemistry [31], may be discussed. One of the important methods of the synthesis of amino acids is the hydrolysis of the appropriate hydantoins. Racemic 5-substituted hydantoins 15 are easily available from aldehydes using a commonly known synthetic procedure (Scheme 5.10) [32]. In the next step, they are enantioselectively hydrolyzed by d- or L-specific hydantoinase and the resulting N-carbamoyl amino acids 16 are hydrolyzed to optically pure a-amino acid 17 by other enzymes, namely, L- or D-specific carbamoylase. This process was introduced in the 1970s for the production of L-amino acids 17 [33]. For many substrates, the racemization process is too slow and in order to increase its rate enzymes called racemases are used. In processes the three enzymes, racemase, hydantoinase, and carbamoylase, can be used simultaneously this enables the production of a-amino acids without isolation of intermediates and increases the yield and productivity. Unfortunately, the commercial application of this process is limited because it is based on L-selective hydantoin-hydrolyzing enzymes [34, 35]. For production of D-amino acid the enzymes of opposite stereoselectivity are required. A recent study indicates that the inversion of enantioselectivity of hydantoinase, the key enzyme in the... 

Polysaccharide degrading enzymes have a long history of commercial application in food processing, horticulture, agriculture, and protein research. As with most other industrial enzymes, the economic use of polysaccharidases often depends on obtaining the maximum activity lifetime in the process environment and/or securing a recovery system that permits the sensible reuse of active enzymes from process streams. 

The commercial availability of enzymes or whole cell biocatalysts for a desired biotransformation is freqnently a limiting factor for commercial application of biocatalysts. Enzymes that are cheaply available are typically used in detergents, processing of food, feed and textiles, as well as in waste management applications. Most of these are hydrolytic enzymes, bnt also isomerases (e.g. glucose isomerase) and oxidorednctases are used on indnstrial scale (Table 5.1). 

When looking for a suitable biocatalyst, one has also to consider the (operational) activity that is required for commercial application and the operational conditions that will be used in the process (e.g. temperature, salt concentration, pH, organic solvents, substrate and product concentration) will have to be addressed as well. If the reaction is optimally performed at for instance high temperatures, thermophilic organisms are more likely to provide the desired enzymes than mesophilic strains (see paragraph 5.4.1). And vice versa, /isychrophiles operate well at lower temperatures and, since they do not require excessive heat treatment to be inactivated, are easily killed following the process. 

In addition to being necessary for all forms of life, biopolymers, especially enzymes (proteins), have found commercial applications in various analytical techniques (see Automated instrumentation, clinical chemistry Automated instrumentation, hemtatology Biopolymers, analytical techniques Biosensors Immunoassay) in synthetic processes (see Enzyme applications, industrial Enzyme applications in organic synthesis) and in prescribed therapies (see Enzyme applications, THERAPEUTICS IMMUNOTHERAPEUTIC AGENTS Vitamins). Other naturally occurring biopolymers having significant commercial importance are the cellulose (qv) derivatives, eg, cotton (qv) and wood (qv), which are complex polysaccharides. 

There are various methods which have been developed for enzyme and microorganism immobilisation and some of these have found commercial application. 

Control of Juice Bitterness. A number of advances have been reported in this field since it was last reviewed (3). A commercial application of the cellulose acetate adsorption technique for the removal of limonin from citrus juices was undertaken (49). New sorbent gel forms of cellulose esters for adsorption of limonin were developed (50). Knowledge was gained that limonoids are biosynthesized in citrus leaves and translocated to the fruit (12) and that specific bioregulators can inhibit accumulation of XIV in citrus leaves (15). Additional studies were carried out on the use of neodiosmin to suppress limonin and other types of bitterness (30,51). The influence of extractor and finisher pressures on the level of limonin and naringin in grapefruit juice was reported (34). Also, further studies were conducted on the microbial sources and properties of limonoate dehydrogenase (52), the enzyme that converts XIV to XV and can be used to prevent limonin from forming in freshly expressed citrus juices (53). 

Researchers at Degussa AG focused on an alternative means towards commercial application of the Julia-Colonna epoxidation [41]. Successful development was based on design of a continuous process in a chemzyme membrane reactor (CMR reactor). In this the epoxide and unconverted chalcone and oxidation reagent pass through the membrane whereas the polymer-enlarged organocatalyst is retained in the reactor by means of a nanofiltration membrane. The equipment used for this type of continuous epoxidation reaction is shown in Scheme 14.5 [41]. The chemzyme membrane reactor is based on the same continuous process concept as the efficient enzyme membrane reactor, which is already used for enzymatic a-amino acid resolution on an industrial scale at a production level of hundreds of tons per year [42]. 

For mycotoxin analyses radioimmunoassay (RIA), enzyme-linked immunosorbent assay (ELISAs) and affinity chromatography are the principal immunochemical methods in commercial application. Immunoaffinity columns or cartridges for specific mycotoxins are now being increasingly used in preliminary clean-up of extracts prior to final analysis by HPLC or GLC methods. 

The first large-scale commercial application of cross-linked enzyme crystals was the use of glucose isomerase CLCs to produce high-fructose com syrup. While this is not a pharmaceutical or a biotechnological application, it is included here because it serves to demonstrate the economic viability of the technology in a very cost-sensitive business. In this application the CLCs were attached to the surface of a polystyrene-cellulose-titanium oxide composite carrier in a ratio of 9 1 carrier enzyme. The catalyst had a half-life of 150 days at 57°C, and 12-18 tons of dry sugar product could be produced per kilogram of enzyme [37],... 

This book gathers and analyzes information of both basic and applied aspects of heme peroxidases. Peroxidases are oxidoreductases that catalyze the oxidation of a wide range of molecules, using peroxide as electron acceptor. Although they have been proposed for applications in several fields (see for example [8, 9]) there are few industrial processes that utilize peroxidases. The commercial applications of these enzymes are reduced to diagnosis and research [10]. Unfortunately, the... 

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