1. Functional characterization of a novel dactylosporangium esterase and its utilization in the asymmetric synthesis of (r)-methyl mandelate.
Aijun Sun, Yunfeng Hu, Dun Deng, Yun Zhang. Appl Biochem Biotechnol. 2016 Sep; 180(2): 228-47. DOI: 10.1007/s12010-016-2095-7. PMID: 27118549.
One novel esterase DAEst6 was identified from the genome of Dactylosporangium aurantiacum subsp. Hamdenensis NRRL 18085. DAEst6 was further characterized to be an esterase which exhibited high resistance to high pH values. Esterase DAEst6 could resolve racemic methyl mandelate and generate (R)-methyl mandelate, one key drug intermediate, with an enantiomeric excess and a conversion of 99 and 49 %, respectively, after process optimization. The optimal working condition for the preparation of (R)-methyl mandelate through DAEst6 was found to be 10-mM racemic methyl mandelate, no organic co-solvents, pH 7.5, and 40 °C, for 5 h. Our work was the first report about the functional characterization of one novel Dactylosporangium esterase and the utilization of one Dactylosporangium esterase in kinetic resolution. Dactylosporangium esterases represented by DAEst6 possess great potential in the generation of valuable chiral drug intermediates and chemicals.
2. Integration of newly isolated biocatalyst and resin-based in situ product removal technique for the asymmetric synthesis of (r)-methyl mandelate.
Jin-Ling Guo, Yan Xu, Xiao-Qing Mu. Bioprocess Biosyst Eng. 2010 Sep; 33(7): 797-804. DOI: 10.1007/s00449-009-0401-2. PMID: 20033429.
The enantioselective reduction of methyl benzoylformate to (R)-methyl mandelate, an important pharmaceutical intermediate and a versatile resolving agent, was investigated in this study. After minimizing the reaction-specific constraints (constraints dependent on the nature of the substrate and product) by preliminary selection of the reaction parameters, an effective whole cell biocatalyst (Saccharomyces cerevisiae AS2.1392) was obtained by simple screening procedures. Under further optimized conditions, a product concentration of 103 mmol L(-1) could be attained within 5 h with a yield of 85.8% and an enantiometric excess of 95.4%, indicating S. cerevisiae AS2.1392 an efficient biocatalyst for the asymmetric synthesis of (R)-methyl mandelate. Furthermore, resin-based in situ product removal (ISPR) technique was applied to alleviate the substrate and product inhibition or toxicity to the whole cells. The integration of newly isolated biocatalyst and proper ISPR technique provides a practical route for the preparation of optically active pharmaceutical intermediates.
3. Functional characterization of a novel dactylosporangium esterase and its utilization in the asymmetric synthesis of (r)-methyl mandelate.
Aijun Sun, Yunfeng Hu, Dun Deng, Yun Zhang. Appl Biochem Biotechnol. 2016 Sep; 180(2): 228-47. DOI: 10.1007/s12010-016-2095-7. PMID: 27118549.
One novel esterase DAEst6 was identified from the genome of Dactylosporangium aurantiacum subsp. Hamdenensis NRRL 18085. DAEst6 was further characterized to be an esterase which exhibited high resistance to high pH values. Esterase DAEst6 could resolve racemic methyl mandelate and generate (R)-methyl mandelate, one key drug intermediate, with an enantiomeric excess and a conversion of 99 and 49 %, respectively, after process optimization. The optimal working condition for the preparation of (R)-methyl mandelate through DAEst6 was found to be 10-mM racemic methyl mandelate, no organic co-solvents, pH 7.5, and 40 °C, for 5 h. Our work was the first report about the functional characterization of one novel Dactylosporangium esterase and the utilization of one Dactylosporangium esterase in kinetic resolution. Dactylosporangium esterases represented by DAEst6 possess great potential in the generation of valuable chiral drug intermediates and chemicals.
