Study on the Asymmetric Synthesis of Chiral 3,3,3-Trifluoro-2-Hydroxypropanoic Acids by Lactate Dehydrogenase.

Chiral 3,3,3-trifluoro-2-hydroxypropanoic acid (3,3,3-trifluorolactic acid, TFLA), which possesses two significant functional groups, is a versatile intermediate in pharmaceutical and material synthesis. A feasible strategy for producing both the enantiomers of chiral TFLAs involves reduction of the corresponding pyruvate using lactate dehydrogenases (LDHs). In this study, ldh genes encoding l-LDHs from animals and d/l-LDHs from lactic acid bacteria are cloned and all the recombinant LDHs are successfully expressed with a histidine tag in Escherichia coli BL21 (DE3). To achieve cofactor regeneration, a nicotinamide adenine dinucleotide regeneration system is constructed using formate dehydrogenase from Candida boidinii. Chiral TFLA is synthesized from 3,3,3-trifluoro-2-oxopropionic acid (trifluoropyruvic acid, TFPy) with good yields and excellent stereoselectivity, catalyzed by lactate dehydrogenases and formate dehydrogenase. Under optimized biocatalytic conditions, highly active d-LmLDH from Leuconostoc mesenteroides and chicken l-LDH from Gallus are screened for their ability to completely convert 0.5 m TFPy to produce optically pure (S)-TFLA and (R)-TFLA with enantiomeric excess >99.5% within 6 h, respectively. Molecular docking simulations investigate the catalytic mechanisms of selected d-LDH and l-LDH, revealing their activity and stereoselectivity toward CF3-containing TFPy.