Enzymatic process development

V.Sandford. Enzymatic Process Development for R-PAC An Intermediate for Ephedrine and Pseudoephedrine Production. PhD Thesis UNSW (2002). 

As the understanding of specific enzymatic processes develops, both in the sense of their mechanisms and of their significance in human and pathogen biochemistry, the need for highly efficient and specific inhibitors will increase. An example of what is likely to be developed in the... 

The major advantage of enzymatic processes is the possibility of using conventional technology already existing in textile plants. Enzyme formulations should be applied in solution, to avoid dust formation and to reduce the known allergizing potential of protein material when inhaled. A heat treatment is sufficient to stop the enzymatic action irreversibly. Thus the transfer of an enzymatic process developed on laboratory scale into the textile industry should be possible without great delay. 

AH cephalosporins found in nature (Tables 1 and 2) have the D-a-aminoadipic acid 7-acyl side chain (21). AH of these compounds can be classified as having rather low specific activity. A substantial amount of the early work in the cephalosporin area was unsuccessfiiHy directed toward replacing the aminoadipic acid side chain or modifying it appropriately by fermentation or enzymatic processes (6,22). A milestone ia the development of cephalosporins occurred in 1960 with the discovery of a practical chemical process to remove the side chain to afford 7-ACA (1) (1). Several related processes were subsequendy developed (22,23). The ready avaHabHity of 7-ACA opened the way to thousands of new semisynthetic cephalosporins. The cephalosporin stmcture offers more opportunities for chemical modification than does that of penicillins There are two side chains that especiaHy lend themselves to chemical manipulation the 7-acylamino and 3-acetoxymethyl substituents. 

The detergent industry is the largest user of industrial enzymes. The starch industry, the first significant user of enzymes, developed special symps that could not be made by means of conventional chemical hydrolysis. These were the first products made entirely by enzymatic processes. Materials such as textiles and leather can be produced in a more rational way when using enzyme technology. Eoodstuffs and components of animal feed can be produced by enzymatic processes that require less energy, less equipment, or fewer chemicals compared with traditional techniques. 

Deussen, H.-J., Zundel, M., Valdois, M. et al. (2003) Process Development on the Enantioselective Enzymatic Hydrolysis of S-Ethyl 2-Ethoxy-3-(4-hydroxyphenyl)Propanoate. Organic Process Research Development, 7, 82-87. 

Tao, J.H. and McGee, K. (2004) Development of a continuous enzymatic process for the preparation of (R)-3-(4-fluorophenyl)-2-hyroxy propionic acid. Organic Process Research Development, 6, 520-524. 

Erdelyi, B., Szabo, A., Birincsik, L. and Hoschke A. (2004) Process development of methylenedioxyphenyl-acetone chiral bioreduction. Journal of Molecular Catalysis B, Enzymatic, 29 (1-6), 195-199. 

A classical approach to driving the unfavorable equilibrium of an enzymatic process is to couple it to another, irreversible enzymatic process. Griengl and coworkers have applied this concept to asymmetric synthesis of 1,2-amino alcohols with a threonine aldolase [24] (Figure 6.7). While the equilibrium in threonine aldolase reactions typically does not favor the synthetic direction, and the bond formation leads to nearly equal amounts of two diastereomers, coupling the aldolase reaction with a selective tyrosine decarboxylase leads to irreversible formation of aryl amino alcohols in reasonable enantiomeric excess via a dynamic kinetic asymmetric transformation. A one-pot, two-enzyme asymmetric synthesis of amino alcohols, including noradrenaline and octopamine, from readily available starting materials was developed [25]. 

In an effort to develop easy-to-use ketoreductase toolbox , we have surveyed the activity and enantioselectivity of a collection of ketoreductases (KRED) from various sources toward the reduction of a variety of ketones [90,91]. These studies served as a useful guideline for developing enzymatic processes for the production of optically pure chiral alcohols. For example, several chiral chlorohydrins of pharmaceutical importance were synthesized in both enantiomeric forms using the enzymes in this ketoreductase collection (Table 7.2) [92]. Further applications of this collection and other commercially available ketoreductases can be found in a recent review [9]. 

At the beginning of the 1990s, Houston Industries developed an enzymatic process ( Enzymatic Coal Desulfurization ) protected in Canada and US [83,84], Although, the application was focused to coal desulfurization it may also be applicable to crude oil and fossil fuel-derived liquids. The processes claim the removal of both, organic as well as inorganic sulfur species. The process was described as using ground coal (10-50 p,m) slurried with water, while the oil was treated in an aqueous emulsion. 

The enzymatic processes involved in the formation of catecholamines have been characterized. The component enzymes in the pathway have been purified to homogeneity, which has allowed for detailed analysis of their kinetics, substrate specificity and cofactor requirements and forthe development of inhibitors (Fig. 12-l).TheircDNAs have been cloned, and studies with knockout mice clearly indicate the importance of these enzymes since their... 

Yazbeck D, Martinez C, Hu S, Tao J (2004) Challenges in the development of an efficient enzymatic process for the pharmaceutical industry. Tetrahedron Asym 15 2757-2763... 

In the remaining part of our presentation of the formal kinetics of enzyme isotope effects a few more complicated examples will be discussed. The methods developed here should be also useful for unraveling other complicated enzyme reactions, and in reading and understanding the modern literature on isotope effects on enzymatic processes. 

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