Zhang_2019_Int.J.Biol.Macromol_140_358

An intracellular esterase (BCE) from Bacillus cereus WZZ006 was purified to homogeneity with an 89.5-fold purification, specific activity of 1.79U/mg, and 26.7% recovery. The estimated molecular weight of BCE was 96kDa 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 pH8.5 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 Km, Vmax, kcat and kcat/Km value for BCE was found to be 0.98mM, 0.03mM/min, 69.47min(-1) and 70.89mM(-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 3h compared to 36h 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.