Dou_2020_Bioresour.Technol_317_123984

A novel carboxylesterase AcEst1 was identified from Acinetobacter sp. JNU9335 with high efficiency in the biosynthesis of chiral precursor of Edoxaban through kinetic resolution of methyl 3-cyclohexene-1-carboxylate (CHCM). Sequence analysis revealed AcEst1 belongs to family IV of esterolytic enzymes and exhibits <40% identities with known carboxylesterases. The optimum pH and temperature of recombinant AcEst1 are 8.0 and 40 degC. Substrate spectrum analysis indicated that AcEst1 prefers substrates with short acyl and alcohol groups. AcEst1 was highly active in the hydrolysis of CHCM with k(cat) of 1153 s(-1) and displayed high substrate tolerance. As much as 2.0 M (280 g.L(-1)) CHCM could be enantioselectively hydrolyzed into (S)-CHCM by merely 0.08 g.L(-1)AcEst1 with ee(s) of >99% (S) and substrate to catalyst ratio (S/C) of 3500 g.g(-1). These results indicate that the novel AcEst1 is a promising biocatalyst in the synthesis of chiral carboxylic acids.