Functional Characterization of a Robust Marine Microbial Esterase and Its Utilization in the Stereo-Selective Preparation of Ethyl (S)-3-Hydroxybutyrate

Abstract

One novel microbial esterase PHE21 was cloned from the genome of Pseudomonas oryzihabitans HUP022 identified from the deep sea of the Western Pacific. PHE21 was heterologously expressed and functionally characterized to be a robust esterase which behaved high resistance to various metal ions, organic solvents, surfactants, and NaCl. Despite the fact that the two enantiomers of ethyl 3-hydroxybutyrate were hard to be enzymatically resolved before, we successfully resolved racemic ethyl 3-hydroxybutyrate through direct hydrolysis reactions and generated chiral ethyl (S)-3-hydroxybutyrate using esterase PHE21. After process optimization, the enantiomeric excess, the conversion rate, and the yield of desired product ethyl (S)-3-hydroxybutyrate could reach 99, 65, and 87 %, respectively. PHE21 is a novel marine microbial esterase with great potential in asymmetric synthesis as well as in other industries.

Utilization of deep‐sea microbial esterase PHE21 to generate chiral sec‐butyl acetate through kinetic resolutions

“…The results showed that both the enantiomeric excess of ( S )‐sec‐butyl acetate and the conversion were decreased by almost all the tested organic solvents and surfactants. However, the presence of Triton X‐100 at the concentration of 0.01% greatly promoted the kinetic resolution of (±)‐ethyl 3‐hydroxybutyrate by esterase PHE21 . The results indicated that the addition of organic solvents and surfactant might strongly affected both the activity and the stereoselectivity of esterase PHE21 by affecting the substrate solubility and the structure of esterase PHE21 .…”

“…But before our study, the reports about the asymmetric synthesis of chiral secondary butanols and their ester derivatives through kinetic resolutions using esterases as the biocatalysts were very rare, possibly because the chemical structure of secondary butanol is quite small and the structural difference on both sides of the secondary alcohols are too small to be recognized by esterases. We previously identified and characterized 1 novel esterase PHE21 from Pseudomonas oryzihabitans HUP022 isolated from the deep sea of the Western Pacific Ocean . Esterase PHE21 was used as a green biocatalyst to generate chiral ethyl ( S )‐3‐hydroxybutyrate, 1 key chiral chemical, with high enantiomeric excess and yield, through direct hydrolysis of racemic ethyl‐3‐hydroxybutyrate.…”

Functional characterization of salt‐tolerant microbial esterase WDEst17 and its use in the generation of optically pure ethyl (R)‐3‐hydroxybutyrate

“…Herein, we developed esterase WDEst17 as a green biocatalyst in the kinetic resolution of (±)‐ethyl 3‐hydroxybutyrate through direct hydrolytic reactions and generated ethyl ( R )‐3‐hydroxybutyrate with high enantiomeric excess ( ee s > 99%) and conversion rate (65.05%) after process optimization. Notably, the enantio‐selectivity of esterase WDEst17 was opposite than that of esterase PHE21 during the kinetic resolution of (±)‐ethyl 3‐hydroxybutyrate from our previous report . The protein sequence analysis showed that both WDEst17 and PHE21 belong to the α/β hydrolase family with the conserved signature (Gly‐X‐Ser‐X‐Gly) in the open reading frames (Figure S7).…”

“…Many novel esterases/lipases may be identified from microorganisms and further developed as biocatalysts for the generation of valuable chiral drug intermediates or chemicals . We previously identified and functionally characterized one novel esterase PHE21 from Pseudomonas oryzihabitans HUP022 . Esterase PHE21 was further used as a useful biocatalyst in the generation of optically pure ethyl ( S )‐3‐hydroxybutyrate with high enantiomeric excess and high conversion after careful process optimization.…”

“…[14][15][16] We previously identified and functionally characterized one novel esterase PHE21 from Pseudomonas oryzihabitans HUP022. 17 Esterase PHE21 was further used as a useful biocatalyst in the generation of optically pure ethyl (S)-3-hydroxybutyrate with high enantiomeric excess and high conversion after careful process optimization.…”