Abstract: Asymmetric bioreduction of an (E)-bcyano-2, 4-dienoic acid derivative by ene- reductases allowed a shortened access to a precursor of pregabalin [(S)-3-(aminomethyl)-5- methylhexanoic acid] possessing the desired configuration in up to 94% conversion and> 99% ee. Deuterium labelling studies showed that the nitrile moiety was the preferred activating/anchor group in the active site of the enzyme over the carboxylic acid or the ...