Abstract:Objective This study characterized a novel esterase EstE from Streptomyces griseus by heterologous expression in Escherichia coli and systematically evaluates its thermostability, alkaline stability, and the effects of various additives (metal ions, detergents, and organic solvents) on its enzymatic activity to explore its potential for industrial applications.Methods We synthesized the gene estE' encoding the same amino acid sequence as the native gene by optimizing the original sequence of estE from S. griseus. We then constructed the recombinant plasmid carrying the optimized gene by ligating the gene into the pET-28b(+) vector. The esterase EstE was then expressed under the induction of IPTG and purified via Co2+ affinity chromatography. Furthermore, the enzymatic properties of the purified EstE were determined by the p-nitrophenol method, and bioinformatics analysis was performed for this enzyme.Results EstE consisted of 289 amino acid residues, with a molecular weight of 31.6 kDa. It belonged to the GDS(L) family, with Ser16, Asp194, and His224 forming its catalytic triad. The enzyme showed the optimal activity at 40 ℃ and pH 8.5, with the highest catalytic efficiency (specific activity of 61.03 U/mg) observed in the case of p-nitrophenyl acetate as a substrate. EstE demonstrated robust thermostability, with the relative activity of 50% after 156.11 h of incubation at 40 ℃ and 2.67 h of incubation at 100 ℃. Moreover, it showed excellent alkaline stability, with the relative activity exceeding 80% after incubation at pH 8.5 for 100 h. In addition, this enzyme exhibited excellent tolerance to organic solvents, maintaining stable activity in the presence of 30% DMSO.Conclusion A novel esterase EstE from S. griseus is successfully obtained through heterologous expression, demonstrating excellent catalytic properties, thermostability, alkaline stability, and organic solvent tolerance, positioning it as a promising candidate for industrial applications.
