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RISS 인기검색어
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- 저자 : ( Jibin Sun ) (검색결과 4 건)
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Ru Xia,Manman Sun,Bin Yang,Jiasheng Qian,Peng Chen,Ming Cao,JIBIN MIAO,LIFEN SU 한국고분자학회 2018 폴리머 Vol.42 No.2
A series of the thermal conductive polyamide-6 (PA6) composites filled with boron nitride (BN) were prepared by two methods, including melting method (MM) and solution method (SM). The thermal conductivity, morphology, crystallization behavior, thermal stability, and rheological properties of PA6 composites were investigated. The results showed that the thermal conductivity of two methods increased with increase in the filler content, the thermal conductivity of PA6/BN composites containing 40 wt% BN prepared by melting method was up to 1.02W·m-1·K-1, while the thermal conductivity of PA6/BN composites prepared by solution method was up to 1.44 W·m-1·K-1 at the same filler content.
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Application of Dynamic Regulation to Increase L-Phenylalanine Production in Escherichia coli
Wu, Jie,Liu, Yongfei,Zhao, Sheng,Sun, Jibin,Jin, Zhaoxia,Zhang, Dawei The Korean Society for Microbiology and Biotechnol 2019 Journal of microbiology and biotechnology Vol.29 No.6
Current strategies of strain improvement processes are mainly focused on enhancing the synthetic pathways of the products. However, excessive metabolic flux often creates metabolic imbalances, which lead to growth retardation and ultimately limit the yield of the product. To solve this problem, we applied a dynamic regulation strategy to produce $\text\tiny{L}$-phenylalanine ($\text\tiny{L}$-Phe) in Escherichia coli. First, we constructed a series of Phe-induced promoters that exhibited different strengths through modification of the promoter region of tyrP. Then, two engineered promoters were separately introduced into a Phe-producing strain xllp1 to dynamically control the expression level of one pathway enzyme AroK. Batch fermentation results of the strain xllp3 showed that the titer of Phe reached 61.3 g/l at 48 h, representing a titer of 1.36-fold of the strain xllp1 (45.0 g/l). Moreover, the $\text\tiny{L}$-Phe yields on glucose of xllp3 (0.22 g/g) were also greatly improved, with an increase of 1.22-fold in comparison with the xllp1 (0.18 g/g). In summary, we successfully improved the titer of Phe by using dynamic regulation of one key enzyme and this strategy can be applied for improving the performance of strains producing other aromatic amino acids and derived compounds.
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Application of Dynamic Regulation to Increase L-Phenylalanine Production in Escherichia coli
( Jie Wu ),( Yongfei Liu ),( Sheng Zhao ),( Jibin Sun ),( Zhaoxia Jin ),( Dawei Zhang ) 한국미생물생명공학회(구 한국산업미생물학회) 2019 Journal of microbiology and biotechnology Vol.29 No.6
Current strategies of strain improvement processes are mainly focused on enhancing the synthetic pathways of the products. However, excessive metabolic flux often creates metabolic imbalances, which lead to growth retardation and ultimately limit the yield of the product. To solve this problem, we applied a dynamic regulation strategy to produce L-phenylalanine (LPhe) in Escherichia coli. First, we constructed a series of Phe-induced promoters that exhibited different strengths through modification of the promoter region of tyrP. Then, two engineered promoters were separately introduced into a Phe-producing strain xllp1 to dynamically control the expression level of one pathway enzyme AroK. Batch fermentation results of the strain xllp3 showed that the titer of Phe reached 61.3 g/l at 48 h, representing a titer of 1.36- fold of the strain xllp1 (45.0 g/l). Moreover, the L-Phe yields on glucose of xllp3 (0.22 g/g) were also greatly improved, with an increase of 1.22-fold in comparison with the xllp1 (0.18 g/ g). In summary, we successfully improved the titer of Phe by using dynamic regulation of one key enzyme and this strategy can be applied for improving the performance of strains producing other aromatic amino acids and derived compounds.
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Deyu Xu,Jing Zhao,Guoqiang Cao,Jinyu Wang,Qinggang Li,Ping Zheng,Shuxin Zhao,Jibin Sun 한국생물공학회 2018 Biotechnology and Bioprocess Engineering Vol.23 No.1
Phosphoenolpyruvate carboxylase (PEPC) catalyzes the carboxylation of phosphoenolpyruvate (PEP) in the presence of bicarbonate to form oxaloacetate (OAA), and it plays an important role in high-efficient production of OAA-derived metabolites such as lysine, glutamate and succinate. However, PEPCs often suffered from serious feedback inhibition by various metabolic effectors like aspartate. Here, the feedback inhibition of PEPC from Corynebacterium glutamicum was removed by adding a short terminal peptide like His-tag. The effect of His-tag location on the structure and important properties such as activity, thermostability and feedback inhibition of PEPC has been investigated. The purified untagged PEPC, Nterminal His-tagged PEPC (PEPC-N-His) and C-terminal His-tagged PEPC (PEPC-C-His) were characterized. PEPCN- His (439.71/sec/mM) showed a 1.26 and 186-fold higher catalytic efficiency than untagged PEPC (348.59/sec/mM) and PEPC-C-His (2.36/sec/mM), respectively. Both PEPCN- His and untagged PEPC were significantly inhibited by aspartate at the concentrations above 4 mM (residual activities < 10%), while PEPC-C-His was almost desensitized to aspartate within 10 mM (around 90% of residual activity). Structural analysis showed that the extension of C-terminus may cause steric hindrance for aspartate binding with enzymes, leading to the deregulation of feedback inhibition of PEPC-C-His. This study provides a deeper understanding of the effect of terminal fragments on the structure and function of PEPCs, and helps to engineer the feedback inhibition of PEPCs and structurally similar enzymes.
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