Processes via Reductive Amination

The biotransformation of prochiral a-keto acids into the corresponding L-amino acids represents an interesting asymmetric reaction for the production of L-a-ami-no acids. In this reaction two enzymes, namely leucine dehydrogenase (LeuDH 

The use of an LeuDH as an amino acid dehydrogenase showed a high L-enan-tiospecificity [24]. In this connection, an L-leucine dehydrogenase from Bacillus sphaericus has been applied very efficiently. The FDH from Candida boidinii is the preferred formate dehydrogenase for this process. The stability of this enzyme, which is available in technical quantities, has been remarkably improved by protein engineering and directed evolution [25], In particular the replacement of cys- 

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