An improved racemase/acylase biotransformation for the preparation of enantiomerically pure amino acids.

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.

Citation

Scott Baxter, Sylvain Royer, Gideon Grogan, Fraser Brown, Karen E Holt-Tiffin, Ian N Taylor, Ian G Fotheringham, Dominic J Campopiano. An improved racemase/acylase biotransformation for the preparation of enantiomerically pure amino acids. Journal of the American Chemical Society. 2012 Nov 28;134(47):19310-3

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PMID: 23130969

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