ChKRED20 is a robust NADH-dependent ketoreductase identified from the genome of Chryseobacterium sp. CA49 that can use 2-propanol as the ultimate reducing agent. The wild-type can reduce over 100 g/l ketones for some pharmaceutical relevant substrates, exhibiting a remarkable potential for industrial application ...
ChKRED20 is a robust NADH-dependent ketoreductase identified from the genome of Chryseobacterium sp. CA49 that can use 2-propanol as the ultimate reducing agent. The wild-type can reduce over 100 g/l ketones for some pharmaceutical relevant substrates, exhibiting a remarkable potential for industrial application. In this work, to overcome the limitation of ChKRED20 to aryl ketoesters, we first refined the X-ray crystal structure of ChKRED20/NAD + complex at a resolution of 1.6 Å, and then performed three rounds of iterative saturation mutagenesis at critical amino acid sites to reshape the active cavity of the enzyme. For methyl 2-oxo-2-phenylacetate and ethyl 3-oxo-3-phenylpropanoate, several gain-of-activity mutants were achieved, and for ethyl 2-oxo-4-phenylbutanoate, improved mutants were achieved with k cat /K m increasing to 196-fold of the wild-type. All three substrates were completely reduced at 100 g/l loading catalyzed with selected ChKRED20 mutants, and deliver the corresponding chiral alcohols with >90% isolated yield and 97 - >99%ee.
Organizational Affiliation:
Key Laboratory of Environmental and Applied Microbiology, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, China; Environmental Microbiology Key Laboratory of Sichuan Province, Chengdu, 610041, China. Electronic address: wuzhl@cib.ac.cn.
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