Purification and characterization of a thermoalkaliphilic esterase from Bacillus cereus WZZ006 for enantioselective resolution of indoxacarb intermediate
An intracellular esterase (BCE) from Bacillus cereus WZZ006 was purified to homogeneity with an 89.5-fold purification , specific activity of 1.79 U/mg, and 26.7% recovery. The estimated molecular weight of BCE was 96 kDa which was analyzed by SDS-PAGE and MALDI-TOF-MS. Activity staining denotes that BCE has an unexplored new carboxyl esterase characteristic. BCE enzyme activity was maximum at pH 8.5 and also at 50 °C with p NP-caproate as a substrate. This indicates that the studied BCE as a thermoalkaliphilic esterase. The kinetic properties like K m , V max , k cat and k cat/ K m value for BCE was found to be 0.98 mM, 0.03 mM/min, 69.47 min −1 and 70.89 mM −1 min −1 , respectively. Synthesis of ( S )-5-chloro-1-oxo-2,3-dihydro-2-hydroxy-1H-indole-2-carboxylic acid methyl ester (( S )-CODHCM) by BCE can be shortened to 3 h compared to 36 h with whole-cell catalysis. The e.e. s achieved was 93.83%, and conversion around 52.78% with E being 39.95. These features render BCE as a promising biocatalyst for the synthesis of a key chiral intermediate for indoxacarb.
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