Enzymes — artificial manufacture

There are thousands of breweries worldwide. However, the number of companies using fermentation to produce therapeutic substances and/or fine chemicals number well over 150, and those that grow microorganisms for food and feed number nearly 100. Lists of representative fermentation products produced commercially and the corresponding companies are available (1). Numerous other companies practice fermentation in some small capacity because it is often the only route to synthesize biochemical intermediates, enzymes, and many fine chemicals used in minor quantities. The large volume of L-phenylalanine is mainly used in the manufacture of the artificial dipeptide sweetener known as aspartame [22389-47-0]. Prior to the early 1980s there was httle demand for L-phenyl alanine, most of which was obtained by extraction from human hair and other nonmicrobiological sources. 

For the first time, the use of artificial enzyme membranes allows the study of the interaction between enzyme activity and membrane potential in a well-defined context. Before the recent progress in manufacturing artificial membrane bearing immobilized enzyme, Blumenthal et al.21 described a system in which a papain solution was sandwiched between two cation and anion exchange membranes. Under short-circuit conditions the system was able to generate a current. A nonequiLbrium thermodynamic analysis was developed by the authors. 

Thermolysin, which is another protease, will also catalyse peptide synthesis, and a new plant will shortly use this enzyme for the manufacture of the artificial sweetener Aspartame, at a scale of2,000 tonnes per year. In this reaction the L-enantiomer of racemic phenylalanine methyl ester reacts specifically with the a-carboxyl group of JV-protected L-aspartate (Scheme 6.26). Thus both the separation of the enantiomers of the phenylalanine and the protection of the y-carboxyl group of the L-aspartate are unnecessary, which simplifies the synthesis. Although the equilibrium favours hydrolysis rather than synthesis, the peptide product, which is the JV-protected precursor ester of Aspartame, forms an insoluble salt with the... 

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