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Your search keyword '"Dong, Jinjun"' showing total 26 results
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26 results on '"Dong, Jinjun"'

20. Carbonyl group-dependent high-throughput screening and enzymatic characterization of diaromatic ketone reductase

Author

Ye Ni, Zhou Jieyu, Weiguo Zhang, Rongzhen Zhang, Ruizhi Han, Dong Jinjun, and Guochao Xu

Subjects
chemistry.chemical_classification, Ketone, Carbonyl Reductase, 010405 organic chemistry, High-throughput screening, Kinetics, Enantioselective synthesis, Reductase, 010402 general chemistry, 01 natural sciences, Catalysis, 0104 chemical sciences, Absorbance, chemistry, Organic chemistry
Abstract

We have developed a carbonyl group-dependent colorimetric method for assay of carbonyl reductases using inexpensive 2,4-dinitrophenylhydrazine (DNPH). This DNPH method has high sensitivity and low background disturbance, and can be used for high-throughput screening of carbonyl reductases toward various ketones including diaromatic ketones, aliphatic ketones/diketones, and aromatic ketones. For 1-(4′-chlorophenyl)-1-(pyridine-2′-yl)-methyl ketone (CPMK), a characteristic absorbance peak at around 500 nm was observed for the product of CPMK and DNPH with a molar absorbance coefficient of 13 750 L mol−1 cm−1. Significantly, this method is also amendable to whole-cell systems for facile high-throughput screening and substrate specificity profiling. In random mutagenesis of a diaromatic ketone reductase KpADH, three variants (M131F, S196Y and S237A) with improved activity toward CPMK were identified using the DNPH method. The substrate specificity of KpADH and its variants toward sixteen prochiral ketones was well characterized. Furthermore, kinetics and molecular docking analyses of KpADH and its variants were performed to elucidate the potential catalytic and enantioselective mechanisms. Consequently, our study provides a rapid screening and characterization method for carbonyl reductases with potential applications in the preparation of optically active secondary alcohols.

Published
2016
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25. [Construction of butanol-producing pathway from Clostridium saccharobutylicum in Escherichia coli JM109 (DE3) and its fermentation].

Author

Li J, Han R, Xu G, Dong J, and Ni Y

Subjects
Bacterial Proteins metabolism, Biosynthetic Pathways, Clostridium genetics, Fermentation, Metabolic Engineering, 1-Butanol metabolism, Bacterial Proteins genetics, Clostridium enzymology, Escherichia coli genetics, Escherichia coli metabolism
Abstract

Objective: ] Several key genes (thlA, bcs-operon/crt-bcd1 -etfB2-fixB2-hbd and adhE) in butanol pathway from Clostridium saccharobutylicum DSM13864 were cloned, and a butanol-producing Escherichia coli strain was successfully constructed., Methods: Using genome of Clostridium saccharobutylicum DSM13864 as template, the key genes in butanol synthesis pathway were amplified, the recombinant plasmids pETDuet-bcs and pRSFDuet-thlA-adhE were constructed. Then the resultant plasmids were transformed into E. coli JM109 (DE3) to obtain E. coli BUT1 for butanol production, under the semi-anaerobic condition. Effects of different mediums on butanol production were studied., Results: The recombinant E. coli was capable of producing butanol (25.4 mg/L) under semi-anaerobic fermentation. After optimization on the fermentation medium, butanol titer reached 34.1 mg/L., Conclusion: Butanol production by recombinant E. coli harboring exogenous butanol-producing pathway from Clostridium saccharobutylicum provides a feasible solution to overcome the hurdles in traditional butanol production approach by Clostridia.

Published
2015

26. [Breeding of monofluoroacetate-resistant strains of Actinobacillus succinogenes and the mechanism based on metabolic flux analysis].

Author

Liu Y, Zheng P, Ni Y, Dong J, Wei P, and Sun Z

Subjects
Actinobacillus growth & development, Actinobacillus metabolism, Fermentation, Metabolic Networks and Pathways, Actinobacillus genetics, Drug Tolerance, Fluoroacetates metabolism, Mutation, Succinic Acid metabolism
Abstract

Succinic acid has received a great deal of attention as an important green chemical stock for the manufacture of synthetic resins, biodegradable polymers and chemical intermediates. In this paper, the breeding mechanism of Actinobacillus succinogenes based on metabolic flux analysis was demonstrated to improve the yield of succinic acid by fermentation. After the NTG treatment, mutants from A. succinogenes CGMCC 1593 which were able to grow in medium containing concentrations of about 50-100 mmol/L of sodium monofluoroacetate were obtained. Among them, a mutant SF-9 was selected for producing more succinic acid and less acetic acid. When fermentations were conducted in a 5 L bioreactors, the final succinic acid concentration of SF-9 (34.8 g/L) increased 23.4%, and the mass ratio of succinic acid/acetic acid increased from 3.3 to 9 compared with those of the parent strain. Based on the metabolic flux analysis of A. succinogenes, PEP was found to be a key node which has an important effect on the production of succinic acid, and the flux ratio of by-productions (acetic, formic, lactic acid) was influenced by PYR node. Compared with the parent strain, the flux to succinic acid of mutant (A. succinogenes SF-9) was significantly increased, while the flux to by-productions had an obvious decline. Therefore, PEP and PYR are not rigid nodes in the metabolic regulation of A. succinogenes.

Published
2008

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