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Directed Evolution of Beta-galactosidase from Escherichia coli into Beta-glucuronidase
Xiong, Ai-Sheng,Peng, Ri-He,Zhuang, Jing,Liu, Jin-Ge,Xu, Fang,Cai, Bin,Guo, Zhao-Kui,Qiao, Yu-Shan,Chen, Jian-Min,Zhang, Zhen,Yao, Quan-Hong Korean Society for Biochemistry and Molecular Biol 2007 Journal of biochemistry and molecular biology Vol.40 No.3
In vitro directed evolution through DNA shuffling is a powerful molecular tool for creation of new biological phenotypes. E. coli $\beta$-galactosidase and $\beta$-glucuronidase are widely used, and their biological function, catalytic mechanism, and molecular structures are well characterized. We applied an in vitro directed evolution strategy through DNA shuffling and obtained five mutants named YG6764, YG6768, YG6769, YG6770 and YG6771 after two rounds of DNA shuffling and screening, which exhibited more $\beta$-glucuronidase activity than wild-type $\beta$-galactosidase. These variants had mutations at fourteen nucleic acid sites, resulting in changes in ten amino acids: S193N, T266A, Q267R, V411A, D448G, G466A, L527I, M543I, Q626R and Q951R. We expressed and purified those mutant proteins. Compared to the wild-type protein, five mutant proteins exhibited high $\beta$-glucuronidase activity. The comparison of molecular models of the mutated and wildtype enzymes revealed the relationship between protein function and structural modification.
Xiong, Ai Sheng,Yao, Quan-Hong,Peng, Ri-He,Li, Xian,Fan, Hui-Qin,Guo, Mei-Jin,Zhang, Si-Liang Korean Society for Biochemistry and Molecular Biol 2004 Journal of biochemistry and molecular biology Vol.37 No.3
Phytases catalyze the release of phosphate from phytic acid. Phytase-producing microorganisms were selected by culturing the soil extracts on agar plates containing phytic acid. Two hundred colonies that exhibited potential phytase activity were selected for further study. The colony showing the highest phytase activity was identified as Aspergillus niger and designated strain 113. The phytase gene from A. niger 113 (phyI1) was isolated, cloned, and characterized. The nucleotide and deduced amino acid sequence identity between phyI1 and phyA from NRRL3135 were 90% and 98%, respectively. The identity between phyI1 and phyA from SK-57 was 89% and 96%. A synthetic phytase gene, phyI1s, was synthesized by successive PCR and transformed into the yeast expression vector carrying a signal peptide that was designed and synthesized using P. pastoris biased codon. For the phytase expression and secretion, the construct was integrated into the genome of P. pastoris by homologous recombination. Over-expressing strains were selected and fermented. It was discovered that ~4.2 g phytase could be purified from one liter of culture fluid. The activity of the resulting phytase was 9.5 U/mg. Due to the heavy glycosylation, the expressed phytase varied in size (120, 95, 85, and 64 kDa), but could be deglycosylated to a homogeneous 64 kDa species. An enzymatic kinetics analysis showed that the phytase had two pH optima (pH 2.0 and pH 5.0) and an optimum temperature of $60^{\circ}C$.
( Ai Sheng Xiong ),( Quan Hong Yao ),( Ri He Peng ),( Xian Li ),( Hui Qin Fan ),( Mei Jin Guo ),( Si Liang Zhang ) 생화학분자생물학회 2004 BMB Reports Vol.37 No.3
Phytases catalyze the release of phosphate from phytic acid. Phytase-producing microorganisms were selected by culturing the soil extracts on agar plates containing phytic acid. Two hundred colonies that exhibited potential phytase activity were selected for further study. The colony showing the highest phytase activity was identified as Aspergillus niger and designated strain 113. The phytase gene from A. niger 113 (phyII) was isolated, cloned, and characterized. The nucleotide and deduced amino acid sequence identity between phyII and phyA from NRRL3135 were 90% and 98%, respectively. The identity between phyII and phyA from SK-57 was 89% and 96%. A synthetic phytase gene, phyIIs, was synthesized by successive PCR and transformed into the yeast expression vector carrying a signal peptide that was designed and synthesized using P. pustoris biased codon. For the phytase expression and secretion, the construct was integrated into the genome of I? pustoris by homologous recombination. Over-expressing strains were selected and fermented. It was discovered that -4.2 g phytase could be purified from one liter of culture fluid. The activity of the resulting phytase was 9.5 U/mg. Due to the heavy glycosylation, the expressed phytase varied in size (120, 95, 85, and 64 kDa), but could be deglycosylated to a homogeneous 64 kDa species. An enzymatic kinetics analysis showed that the phytase had two pH optima (pH 2.0 and pH 5.0) and anoptimum temperature of 60℃.
Paint Removal of Airplane & Water Jet Application
Xue, Sheng-Xiong,Chen, Zheng-Wen,Ren, Qi-Le,Su, Ji-Xin,Han, Cai-Hong,Pang, lei Korean Society for Fluid machinery 2014 International journal of fluid machinery and syste Vol.7 No.3
The paint removal and recoating are the very important process in airplane maintenance. The traditional technology is to use the chemical way corroding the paint with paint remover. For changing the defects, corrosion & pollution & manual working, of the traditional technology, the physical process which removes the paint of airplane with 250MPa/250kW ultra-high pressure rotary water jetting though the surface cleaner installed on the six axes robot is studied. The paint layer of airplane is very thin and close. The contradiction of water jetting paint removal is to remove the paint layer wholly and not damage the surface of airplane. In order to solve the contradiction, the best working condition must be reached through tests. The paint removal efficiency with ultra-high pressure and move speed of not damaged to the surface. The move speed of this test is about 2m/min, and the paint removal efficiency is about $30{\sim}40m^2/h$, and the paint removal active area is 85-90%. No-repeat and no-omit are the base requests of the robot program. The physical paint removal technology will be applied in airplane maintenance, and will face the safety detection of application permission.
Sliding Mode Control for Continuous Casting Mold Oscillatory System Driven by Servo Motor
Sheng-Li Shi,Ke-song Kang,Jian-Xiong Li,Yi-ming Fang 제어·로봇·시스템학회 2017 International Journal of Control, Automation, and Vol.15 No.4
This paper develops an extended-state-observer-based sliding mode control strategy for continuous castingmold oscillatory system driven by servo motor in the presence of matched and mismatched disturbance. Extendedstate observers are employed to estimate the compound disturbances, and the requirement of the derivativeof the compound disturbances to zero is avoided. In order to counteract the mismatched disturbance and attenuatethe chattering phenomenon, a novel sliding surface based on extended state observer is designed for the system. Simulation results illustrate that the proposed controller can achieve better tracking performance and robustness tothe compound disturbance.
Sheng-Li Shi,Jian-Xiong Li,Yi-ming Fang 제어·로봇·시스템학회 2019 International Journal of Control, Automation, and Vol.17 No.5
This paper addresses the sliding mode control for a class of fractional order systems with matched andmismatched disturbances. Firstly, fractional disturbance observer is presented to estimate both the matched andmismatched disturbances, and the boundedness of the estimation error can be guaranteed. Secondly, sliding modesurface is constructed based on the output of the observer. The bounded stability of the closed-loop system underthe designed controller is revealed by theoretical analysis. Finally, simulation results show that the proposed controlstrategy can effectively suppress the effect of the matched and mismatched disturbances on the system.
Sheng Hongxun,Xiong Wenwen,Zheng Songsheng,Chen Chao,He Song,Cheng Qijin 한국탄소학회 2021 Carbon Letters Vol.31 No.5
DLC has been attractive as semiconductor materials for solar cell due to its biological friendliness, fexible microstructures, and especially its tunable band gap. In order to fabricate high-efciency multiband gap solar cell, it is important to control the sp3 / sp2 bonds ratio of DLC flm corresponding to optical band gap (Eg). There are many references reporting the relations among the fabrication conditions, Eg, sp3 /sp2 , and ID/IG. However, a more comprehensive database is needed for controllable fabrication. Especially, the quantitative relationship of sp3 /sp2 ratio to Eg of DLC flm by PECVD is unclear. In this paper, 36 sets of DLC flms were fabricated by RF-PECVD. Characterization methods of XPS, Raman spectroscopy, and IR absorption have been used to determine the sp3 /sp2 ratio of DLC flms. UV/visible light absorption method has applied to evaluate Eg. The Eg obtained is in the range 1.45–3.0 eV. Our results agree well with the references. The XPS spectra gives a linear relationship as Eg=− 0.161 (±0.136)+26.095 (±1.704) · {sp3 (XPS)/sp2 }, the Raman spectra shows a linear function that Eg=1.327 (±0.046)+0.428 (±0.036) · (ID/IG), as well as the FTIR analysis demonstrates that Eg=− 0.492 (±0.093)+0.464 (±0.044) · {sp3 (FTIR)/sp2 }.
Protecting Multicast Sessions in WDM Networks with Sparse-Splitting Constraints
Xiong Wang,Sheng Wang,Lemin Li 한국전자통신연구원 2007 ETRI Journal Vol.29 No.4
In this letter, we study the multicast protection problem in sparse-splitting wavelength-division multiplexing (WDM) optical network, and propose a novel multicast protection algorithm called the shared source-leaf path-based protection (SLPP) algorithm. Unlike the proposals in previous studies, the backup paths derived by SLPP can share wavelength with the primary tree in sparse-splitting WDM networks. Simulations are used to evaluate the effectiveness of the SLPP algorithm.
Sheng HU,Fei Chen,Jun-Guo Li,Qiang Shen,Zhi-Xiong Huang,Lian-Meng Zhang 한양대학교 세라믹연구소 2016 Journal of Ceramic Processing Research Vol.17 No.8
The phase and microstructure evolution of ammonium polyphosphate/ aluminium hydroxide/ mica compounds (AAM) duringthermal reaction are investigated. At 300 oC, AAM residues exhibit porous structure due to gas evolution from the thermaldecomposition of ammonium polyphosphate (APP) and aluminium hydroxide, but mica does not react with them, and theflexural strength of specimens can reach 11.56 MPa. The thermal decomposition products of APP react with AlOOH toNH4AlP2O7, which can improve the flexural strength during 300 ~ 400 oC. The reactivity of mica is increased by eliminatinghydroxyl at temperature up to 600 oC, and the flexural strength of AAM residues is improved furtherly by the chemicallyinteractions between active mica and phosphates during 600 ~ 1000 oC. And specifically at 1000 oC, the AAM residues exhibitrelatively high flexural strength, which can reach 26.85 MPa and reactions between mica and KAlP2O7 could generateKAlSi3O8 and 3Al2O3·2SiO2. AAM with high flexural strength from low to high temperatures is expected to be a kind ofexcellent inorganic additive of ceramifiable polymer with wide temperature range for using.