Enantioselective Biocatalytic Production of L-Amino Acids on an Industrial Scale

Methods for the Enantioselective Biocatalytic Production of L-Amino Acids on an Industrial Scale 

A classic example of a typical enzymatic resolution on an industrial scale is the acylase-mediated production of L-methionine. This method has also been applied for the production of L-phenylalanine and L-valine. In addition to acylases, amidases, hydantoinases, and /i-lactam hydrolases represent versatile biocatalysts for the production of optically active L-amino acids. A schematic overview of the different type of enzymatic resolutions for the synthesis of L-amino acids is given in Fig. 2. 

In addition, the use of a whole-cell biocatalyst consisting of a racemase, hydantoi-nase, and carbamoylase allows a dynamic biocatalytic resolution. Besides resolution processes, asymmetric (bio-)catalytic concepts have been applied successfully on an industrial scale. The different types of asymmetric (bio-)catalytic syntheses of L-amino acids, based on the use of prochiral starting materials, are shown in Fig. 3. 

Using an L-amino acid dehydrogenase in the presence of a formate dehydrogenase for cofactor regeneration, a prochiral keto acid is converted with high yield and en-antioselectivity. Furthermore, biocatalytic transaminations as well as Michael-addi-tions are important reactions for the large-scale synthesis of L-amino acids. 

Asymmetric Catalysis on Industrial Scale Challenges, Approaches and Solutions Edited by H.U. Blaser, E. Schmidt 

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Groger, H., Drauz, K. Methods for the Enantioselective Biocatalytic Production of L-Amino Acids on an Industrial Scale. In Asymmetric Catalysis on Industrial Scale, Blaser, H.-U., Schmidt, E. Eds., Wiley-VCH Weinheim, 2004, p. 131. 

Methods for the enantioselective biocatalytic production of L-amino acids on an industrial scale... 

H. Groeger, K. Drauz, Methods for the Enantioselective Biocatalytic Production of L-amino Acids on an industrial Scale, Wiley-VCH Verlag GmbH Co, KGaA, 2004, pp. 131-147. 

A biocatalytic enantioselective addition of ammonia to a C=C bond of an afl-unsaturated compound, namely fumaric acid, makes the manufacture of L-aspar-tic acid, l-27, possible [30], This L-amino acid represents an important intermediate for the production of the artificial sweetener aspartame. The biocatalytic production process, which is applied on an industrial scale by, e.g., Kyowa Hakko Ko-gyo and Tanabe Seiyaku, is based on the use of an aspartate ammonia lyase [E.C.4.3.1.1] [31]. As a biocatalyst, an immobilized L-aspartate ammonia lyase from Escherichia coli [32, 33] as well as Brevibacterium flavum whole-cell catalysts [32 a, 34] have been applied successfully. 

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