Amino acid dehydrogenases AADHs

Structural Features of Amino Acid Dehydrogenases (AADHs)... 

Enantiomericaiiy pure amino adds have been used as pharmaceutical and agrochemical intermediates [4]. The desired amino adds have been further expanded past the natural production of r-amino adds through fermentation [5]. Reduction of keto acids can be achieved through amino acid dehydrogenases (AADHs) or transaminases (TAs). 

A very promising process route is the reductive amination of prochiral a-keto acids to a-amino acids with AADHs and the cofactor NADH and its regeneration by cooxidation of formate to CO2 by formate dehydrogenase (Fig. 15.3-1). 

Reviews on AADHs Apart from early review articles on individual amino acid dehydrogenases by Schiitte et al. (1985 LeuDH from B. cereus)[61, Ohshima et al. (1985a LeuDH from B. species)171 and Hummel et al. (1987 PheDH from Rh. rhodocrous) 8, comprehensive reviews have been published by Hummel and Kula (1989)[91, Ohshima and Soda (1989 and 1990) l5-10-11 and by Brunhuber and Blanchard (1994) [12>. 

Scheme 8.16 Formal Mitsunobu reaction by combining an alcohol dehydrogenase (here mandelate dehydrogenase, D-MDH) with an amino acid dehydrogenase (here l-AADH).

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