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An Improved Racemase/Acylase Biotransformation for the Preparation of Enantiomerically Pure Amino Acids

Author:
Baxter, Scott, Royer, Sylvain, Grogan, Gideon, Brown, Fraser, Holt-Tiffin, Karen E., Taylor, Ian N., Fotheringham, Ian G., Campopiano, Dominic J.
Source:
Journal of the American Chemical Society 2012 v.134 no.47 pp. 19310-19313
ISSN:
1520-5126
Subject:
X-radiation, acids, amino acids, biotransformation, catalytic activity, directed evolution
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.
Agid:
5387248