Asymmetric hydrolysis of 2-hydroxy-carboxylic esters using recombinant Escherichia coli

Optically active 2-hydroxy-carboxylates are important compounds for their use as intermediates in the synthesis of pharmaceuticals and stereoblock polymers. Enterobacter sp. DS-S-75 and the recombinant Escherichia coli harbouring the 4-chloro-3-hydroxybutyrate (CHB) hydrolase gene from the strain DS-S-75 showed asymmetric hydrolytic activity towards 2-hydroxy-carboxylates, as well as towards CHB. It was discussed that the hydroxyl group in the substrate was particularly important for the asymmetric hydrolytic activity of the CHB hydrolase, and as such, it was re-designated to EnHCH (hydroxy-carboxylic ester hydrolase derived from Enterobacter sp.). Using the recombinant cell, both the reaction rate and the concentration of the substrates were significantly improved upon when compared to that of DS-S-75. Optically active 2-hydroxy-carboxylates could be synthesized on a practical basis for industrial production in this report.

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Methyl (R)-2-hydroxybutyrateC5H10O3Ee >98%[α]D20=+2.45 (neat)Source of chirality: microbial resolutionAbsolute configuration: (R)

(S)-2-Hydroxybutyric acid sodium saltC4H7O3NaEe >98%[α]D20=-10.4 (c 10, H2O)Source of chirality: microbial resolutionAbsolute configuration: (S)

Ethyl (R)-lactateC5H10O3Ee >98%[α]D20=+11.2 (neat)Source of chirality: microbial resolutionAbsolute configuration: (R)

Ethyl (S)-3-hydroxybutyrateC6H12O3Ee >99%[α]D20=+18.0 (neat)Source of chirality: microbial resolutionAbsolute configuration: (S)

(R)-3-Hydroxybutyric acid sodium saltC4H7O3NaEe >99%[α]D20=-14.1 (c 10, H2O)Source of chirality: microbial resolutionAbsolute configuration: (R)

Methyl (R)-tetrahydrofuran-2-carboxylateC6H10O3Ee >98%[α]D20=-17.7 (neat)Source of chirality: microbial resolutionAbsolute configuration: (R)