Industrial biotransformations commercial enzymes

It should be noted that some commercial enzyme preparations may contain several enzyme isomers (enzymes derived from one source which belong to the same enzyme class but differ in specificity, stability or other properties). This is most often the case when the commercial preparation was developed for a process industry application rather than a specific chemical biotransformation application. Some fungal enzymes, such as laccase, are sometimes supplied as crude enzyme mixtures. Fungal laccases are manufactured on a huge scale (multitonne per annum) and are principally used in bulk processes such as wood... 

There are no internationally standard assay methods for industrial enzymes and the definition of enzyme activity unit is also different for each enzyme. The activity of industrial enzymes is shown by various methods depending on manufacturers. For instance, commercial lipase activities are measured by the hydrolysis of olive oil under the various conditions and these figures are not comparable with each other. When customers apply these biocatalysts for chemical synthesis in organic solvents, these figure are sometimes reliable, and sometimes not. Users should not judge commercial enzymes based only on price and the activity shown in the table the manufacturer provides. Enzymes should be evaluated based on their practical performance under the conditions used. Most users of biotransformation are not experts in measuring enzyme activity, so the establishment of an assay method and practice are essential if one is to optimize the performance of enzymes. 

Acrylamide is the first bulk chemical manufactured using an industrial biotransformation. Acrylamide which is produced 200000 t/a is an important industrial chemical that is mainly processed into water-soluble polymers and copolymers, which find applications as flocculants, paper-making aids, thickening agents, surface coatings, and additives for enhanced oil recovery. The chemical manufacture of acrylamide has been established for a long time, it is based on Cu-catalysis. The production of acrylamide using immobilized whole cells of Rhodococcus rhodochrous is a remarkable example of a lyase-catalyzed commercial process. The enzyme responsible for water addition to the double bond of acrylonitrile is nitrile hydratase (Eq. 4-17) ... 

Vasic-Racki, Durda. History of Biotransformations Dreams and Realities. Industrial Biotransformations, edited by Andreas Liese, Karsten Seelbach, and Christian Wandrey. Weinheim, Germany Wiley-VCH Verlag, 2000. This essay chronicles the history of using microorganisms and enzymes to synthesize commercially valuable products and... 

Though use of isolated purified enzymes is advantageous in that undesirable byproduct formation mediated by contaminating enzymes is avoided [37], in many industrial biotransformation processes for greater cost effectiveness the biocatalyst used is in the form of whole cells. For this reason baker s yeast, which is readily available, has attracted substantial attention from organic chemists as a catalyst for biotransformation processes. One of the first commercialized microbial biotransformation processes was baker s yeast-mediated production of (R)-phenylacetyl carbinol, where yeast pyruvate decarboxylase catalyzes acyloin formation during metabolism of sugars or pyruvate in the presence of benzaldehyde [38]. 

One of the reactions catalyzed by esterases and lipases is the reversible hydrolysis of esters (Figure 19.1, Reaction 2). These enzymes also catalyze transesterilications and the desymmetrization of mew-substrates (vide infra). Many esterases and lipases are commercially available, making them easy to use for screening desired biotransformations without the need for culture collections and/or fermentation capabilities.160 In addition, they have enhanced stability in organic solvents, require no co-factors, and have a broad substrate specificity, which make them some of the most ideal industrial biocatalysts. Alteration of reaction conditions with additives has enabled enhancement and control of enantioselectivity and reactivity with a wide variety of substrate structures.159161164... 

One of the oldest methods, solid-state fermentation or the koji process, uses solid substrates, such as steam sterilized fibers or wheat bran, to cultivate the mold inoculum. This technique has been central to traditional food and beverage fermentations throughout Asia for thousands of years. Today solid-state fermentation is the cultivation method of choice for the commercial production of many enzymes and is gaining popularity in areas including bioremediation, detoxification of agro-industrial waste and biotransformation of crop residues for nutritional enrichment (Pandey et al., 2000 Singhania et al., 2009). 

There are many enzymes that are commercially available, though the biotransformation literature and our own experience shows that in fact most biocatalysis is done with a relatively small subset of very frequently used enzymes. For a comprehensive review of biocatalysis in organic synthesis, the reader should refer to Drauz and Waldmann s two-volume Enzyme Catalysis in Organic Synthesis [1]. Many commercially available enzymes were not developed with organic synthesis in mind but are used in other industries. Examples include proteases like subtilisin, used in detergent formulations, or lipases, again used in detergents or in cheese and flavor production. There is a wide variety of ways in... 

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