Highly efficient Michael-type addition of acetaldehyde to ß-nitrostyrenes by whole resting cells of Escherichia coli expressing 4-oxalocrotonate tautomerase.
Bioresour Technol
; 142: 462-8, 2013 Aug.
Article
em En
| MEDLINE
| ID: mdl-23759430
ABSTRACT
A novel whole cell system based on recombinantly expressed 4-oxalocrotonate tautomerase (4-OT) was developed and shown to be an effective biocatalyst for the asymmetric Michael addition of acetaldehyde to ß-nitrostyrenes. Optimal ratio of substrates (2mM ß-nitrostyrenes and 20mM acetaldehyde) and biocatalyst of 5 g of cell dry weight of biocatalyst per liter was determined. Through further bioprocess improvement by sequential addition of substrate 10mM nitrostyrene biotransformation was achieved within 150 min. Excellent enantioselectivity (>99% ee) and product yields of up to 60% were obtained with ß-nitrostyrene substrate. The biotransformation product, 4-nitro-3-phenyl-butanal, was isolated from aqueous media and further transformed into the corresponding amino alcohol. The biocatalyst exhibited lower reaction rates with p-Cl-, o-Cl- and p-F-ß-nitrostyrenes with product yields of 38%, 51%, 31% and ee values of 84%, 88% and 94% respectively. The importance of the terminal proline of 4-OT was confirmed by two proline enriched variants and homology modeling.
Palavras-chave
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Estirenos
/
Escherichia coli
/
Isomerases
/
Acetaldeído
Idioma:
En
Ano de publicação:
2013
Tipo de documento:
Article