A novel carboxylesterase from Acinetobacter sp. JNU9335 for efficient biosynthesis of Edoxaban precursor with high substrate to catalyst ratio

A novel carboxylesterase Ac Est1 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 Ac Est1 belongs to family IV of esterolytic enzymes and exhibits <40% identities with known carboxylesterases. The optimum pH and temperature of recombinant Ac Est1 are 8.0 and 40 °C. Substrate spectrum analysis indicated that Ac Est1 prefers substrates with short acyl and alcohol groups. Ac Est1 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 Ac Est1 with ee s of >99% ( S ) and substrate to catalyst ratio (S/C) of 3500 g·g −1 . These results indicate that the novel Ac Est1 is a promising biocatalyst in the synthesis of chiral carboxylic acids.