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 degrees C with pNP-caproate as a substrate. This indicates that the studied BCE as a thermoalkaliphilic esterase. The kinetic properties like K-m, V-max, kcat and kcat/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-23-dihydro-2-hydroxy-1H-indole-2-carbox-ylic 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. (C) 2019 Published by Elsevier B.V.