%0 Journal Article
%T Immobilization of a Novel ESTBAS Esterase from Bacillus altitudinis onto an Epoxy Resin: Characterization and Regioselective Synthesis of Chloramphenicol Palmitate
%J Catalysts | An Open Access Journal from MDPI
%D 2019
%R https://doi.org/10.3390/catal9070620
%X Novel gene estBAS from Bacillus altitudinis, encoding a 216-amino acid esterase (Est BAS) with a signal peptide (SP), was expressed in Escherichia coli. Est BAS¦¤SP showed the highest activity toward p-nitrophenyl hexanoate at 50 ˇăC and pH 8.0 and had a half-life (T 1/2) of 6 h at 50 ˇăC. Est BAS¦¤SP was immobilized onto a novel epoxy resin (Lx-105s) with a high loading of 96 mg/g. Fourier transform infrared (FTIR) spectroscopy showed that Est BAS¦¤SP was successfully immobilized onto Lx-105s. In addition, immobilization improved its enzymatic performance by widening the tolerable ranges of pH and temperature. The optimum temperature of immobilized Est BAS¦¤SP (Lx-Est BAS¦¤SP) was higher, 60 ˇăC, and overall thermostability improved. T 1/2 of Lx-Est BAS¦¤SP and free Est BAS¦¤SP at 60 ˇăC was 105 and 28 min, respectively. Lx-Est BAS¦¤SP was used as a biocatalyst to synthesize chloramphenicol palmitate by regioselective modification at the primary hydroxyl group. Conversion efficiency reached 94.7% at 0.15 M substrate concentration after 24 h. Lx-Est BAS¦¤SP was stable and could be reused for seven cycles, after which it retained over 80% of the original activity. View Full-Tex
%U https://www.mdpi.com/2073-4344/9/7/620