biostudies-otherUnknown6(4)Chen XChemistryOpen534-540https://www.ebi.ac.uk/biostudies/studies/S-EPMC5542762d-2-Aminobutyric acid is an unnatural amino acid serving as an important intermediate in pharmaceutical production. Developing a synthetic method that uses cheaper starting materials and produces less by-product is a pressing demand. A tri-enzymatic catalytic system, which is composed of l-threonine ammonia lyase (l-TAL), d-amino acid dehydrogenase (d-AADH), and formate dehydrogenase (FDH), has thus been developed for the synthesis of d-2-aminobutyric acid with high optical purity. In this cascade reaction, the readily available l-threonine serves as the starting material, carbon dioxide and water are the by-products. d-2-Aminobutyric acid was obtained with >90 % yield and >99 % enantioselective excess, even without adding external ammonia, demonstrating that the ammonia from the first reaction can serve as the amino donor for the reductive amination step. This multi-enzymatic system provides an attractive method with high atomic economy for the synthesis of d-α-amino acids from the corresponding l-α-amino acids, which are readily produced by fermentation.biostudies-otherEurope PMCFeng JCui YWu QChen XCheng XZhu DfalseHighly Atom Economic Synthesis of d-2-Aminobutyric Acid through an In Vitro Tri-enzymatic Catalytic System.d-2-Aminobutyric acid is an unnatural amino acid serving as an important intermediate in pharmaceutical production. Developing a synthetic method that uses cheaper starting materials and produces less by-product is a pressing demand. A tri-enzymatic catalytic system, which is composed of l-threonine ammonia lyase (l-TAL), d-amino acid dehydrogenase (d-AADH), and formate dehydrogenase (FDH), has thus been developed for the synthesis of d-2-aminobutyric acid with high optical purity. In this cascade reaction, the readily available l-threonine serves as the starting material, carbon dioxide and water are the by-products. d-2-Aminobutyric acid was obtained with >90 % yield and >99 % enantioselective excess, even without adding external ammonia, demonstrating that the ammonia from the first reaction can serve as the amino donor for the reductive amination step. This multi-enzymatic system provides an attractive method with high atomic economy for the synthesis of d-α-amino acids from the corresponding l-α-amino acids, which are readily produced by fermentation.2017-01-01T00:00:00Z2017 Aug2019-08-03T07:40:19Z2019-08-03T07:40:19ZS-EPMC554276210.1002/open.201700093