title: An improved racemase/acylase biotransformation for the preparation of enantiomerically pure amino acids.
abstract: Using directed evolution, a variant N-acetyl amino acid racemase (NAAAR G291D/F323Y) has been developed with up to 6-fold higher activity than the wild-type on a range of N-acetylated amino acids. The variant has been coupled with an enantiospecific acylase to give a preparative scale dynamic kinetic resolution which allows 98% conversion of N-acetyl-DL-allylglycine into D-allylglycine in 18 h at high substrate concentrations (50 g L(-1)). This is the first example of NAAAR operating under conditions which would allow it to be successfully used on an industrial scale for the production of enantiomerically pure α-amino acids. X-ray crystal analysis of the improved NAAAR variant allowed a comparison with the wild-type enzyme. We postulate that a network of novel interactions that result from the introduction of the two side chains is the source of improved catalytic performance.
authors.affiliation: The EastChem School of Chemistry, Joseph Black Building, The University of Edinburgh, Edinburgh, EH9 3JJ, UK.
authors.forename: Scott
authors.initials: S
authors.lastname: Baxter
authors.forename: Sylvain
authors.initials: S
authors.lastname: Royer
authors.forename: Gideon
authors.initials: G
authors.lastname: Grogan
authors.forename: Fraser
authors.initials: F
authors.lastname: Brown
authors.forename: Karen E
authors.initials: KE
authors.lastname: Holt-Tiffin
authors.forename: Ian N
authors.initials: IN
authors.lastname: Taylor
authors.forename: Ian G
authors.initials: IG
authors.lastname: Fotheringham
authors.forename: Dominic J
authors.initials: DJ
authors.lastname: Campopiano
mesh_terms: D000581:Amidohydrolases / Q000737:chemistry / Q000378:metabolism*; D000596:Amino Acids / Q000096:biosynthesis* / Q000737:chemistry; D008958:Models, Molecular; D015394:Molecular Structure; D019998:Racemases and Epimerases / Q000737:chemistry / Q000378:metabolism*; D013237:Stereoisomerism
chemical_list: D000596:Amino Acids; D000581:Amidohydrolases; C019665:amidase; D019998:Racemases and Epimerases