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Molecular and Biochemical Characterization of a Novel Intracellular Low-Temperature-Active Xylanase
( Jun Pei Zhou,),( Yan Yan Dong ),( Xiang Hua Tang ),( Jun Jun Li ),( Bo Xu ),( Qian Wu ),( Ya Jie Gao ),( Lu Pan ),( Zun Xi Huang ) 한국미생물 · 생명공학회 2012 Journal of microbiology and biotechnology Vol.22 No.4
A 990 bp full-length gene (xynAHJ2) encoding a 329- residue polypeptide (XynAHJ2) with a calculated mass of 38.4 kDa was cloned from Bacillus sp. HJ2 harbored in a saline soil. XynAHJ2 showed no signal peptide, distinct amino acid stretches of glycoside hydrolase (GH) family 10 intracellular endoxylanases, and the highest amino acid sequence identity of 65.3% with the identified GH 10 intracellular mesophilic endoxylanase iM-KRICT PX1-Ps from Paenibacillus sp. HPL-001 (ACJ06666). The recombinant enzyme (rXynAHJ2) was expressed in Escherichia coli and displayed the typical characteristics of low-temperatureactive enzyme (exhibiting optimum activity at 35 o C, 62% at 20 o C, and 38% at 10 o C; thermolability at ≥45 o C). Compared with the reported GH 10 low-temperature-active endoxylanases, which are all extracellular, rXynAHJ2 showed low amino acid sequence identities (<45%), low homology (different phylogenetic cluster), and difference of structure (decreased amount of total accessible surface area and exposed nonpolar accessible surface area). Compared with the reported GH 10 intracellular endoxylanases, which are all mesophilic and thermophilic, rXynAHJ2 has decreased numbers of arginine residues and salt bridges, and showed resistance to Ni 2+ , Ca 2+ , or EDTA at 10 mM final concentration. The above mechanism of structural adaptation for low-temperature activity of intracellular endoxylanase rXynAHJ2 is different from that of GH 10 extracellular low-temperature-active endoxylanases. This is the first report of the molecular and biochemical characterizations of a novel intracellular low-temperatureactive xylanase.
( Jun Pei Zhou ),( Qian Wu ),( Rui Zhang ),( Yu Ying Yang ),( Xiang Hua Tang ),( Jun Jun Li ),( Jun Mei Ding ),( Yan Yan Dong ),( Zun Xi Huang ) 한국미생물 · 생명공학회 2013 Journal of microbiology and biotechnology Vol.23 No.6
This paper reports the production and characterization of crude xylanase from the newly isolated Humicola sp. Ly01. The highest (41.8 U/ml) production of the crude xylanase was obtained under the optimized conditions (w/v): 0.5% wheat bran, 0.2% KH2PO4, and 0.5% peptone; initial pH 7.0; incubation time 72 h; 30℃; and 150 rpm. A considerable amount of the crude xylanase was induced using hulless barley bran or soybean meal as the carbon source, but a small amount of the enzyme was produced when supplementary urea was used as the nitrogen source to wheat bran. The crude xylanase showed apparent optimal cellulase-free xylanase activity at 60℃ and pH 6.0, more than 71.8% of the maximum xylanase activity in 3.0-30.0% (v/v) ethanol and more than 82.3% of the initial xylanase activity after incubation in 3.0-30.0% (v/v) ethanol at 30℃ for 2 h. The crude xylanase was moderately resistant to both acid and neutral protease digestion, and released 7.9 and 10.9 μmol/ml reducing sugar from xylan in the simulated gastric and intestinal fluids, respectively. The xylooligosaccharides were the main products of the hydrolysis of xylan by the crude xylanase. These properties suggested the potential of the crude enzyme for being applied in the animal feed industry, xylooligosaccharides production, and high-alcohol conditions such as ethanol production and brewing.
Hua-Ping Lin,Fan Zhou,Jun Li,Xiao-Wen Zhang,Dong-Bin Yu,Liang Zhang,Xue-Yin Jiang,Zhi-Lin Zhang 한국공업화학회 2011 Journal of Industrial and Engineering Chemistry Vol.17 No.4
This work demonstrated the fabrication of white organic light-emitting devices (WOLEDs) using a dual emitting layer (d-EML) consisting of blue and ‘white’ emitters. In this d-EML system, the blue emitter not only emits but also assists the incomplete energy transfer. More importantly, it behaves as an effective trapping site for holes, which contributes to the efficient recombination of electron–hole pairs. The d-EML was constructed between the hole-transmitting layer (HTL) and the electron-transmitting layer (ETL) of Alq3 and BPhen. The thickness of the blue emitter used in the d-EML devices has an important effect on chromaticity and efficiency. Through the optimization of device structure, the reasonable white emission with Commission Internationale de L’Eclairage (CIE) color coordinates of (0.33, 0.33) and little color shift was obtained. The device showed an applicable luminance with its maximum luminance of 22,874 cd/m2 at a driving voltage of 16 V. The maximum luminance efficiency was achieved 8.10 cd/A,and the maximum power efficiency was reached 5.07 Lm/W. The result is explained with the help of the excitons generation and diffusion theory. According to the theory of excitons generation and diffusion,an equation has been set up which concerns electroluminescent spectra to the thickness of the two emitters and to the exciton diffusion length.
Highly Efficient Microwave-assisted Aminolysis of Epoxides in Water
Hua Zuo,Zhu-Bo Li,Bao-Xiang Zhao,Jun-Ying Miao,Li-juan Meng,Kiwan Jang,안철진,Dong-Ha Lee,신동수 대한화학회 2011 Bulletin of the Korean Chemical Society Vol.32 No.8
Highly efficient and rapid aminolysis of epoxides with various amines in water under microwave irradiation in the absence of catalyst was developed. Chiral β-amino alcohols were formed in a short time with excellent yields.
Hua-Ping Lin,Fan Zhou,Xiao-Wen Zhang,Dong-Bin Yu,Jun Li,Liang Zhang,Xue-Yin Jiang,Zhi-Lin Zhang 한국물리학회 2011 Current Applied Physics Vol.11 No.3
A double hole injection layer consisting of Ag_2O//MoO_x was applied to a 4,40-bis (2,2-diphenylvinyl)-1,10-biphenyl-based blue organic light-emitting device (OLED). The hole current injection of the devicewas improved and the performance of the blue OLED was enhanced. We have observed that the insertion of such double layer leads to a striking improvement in chromaticity and electrical characteristics. This device showed much better chromaticity and less current-induced color shift as compared to the corresponding single hole injection layer counterparts. Using this strategy, a striking improvement in the electrical properties with lower driving voltage, higher power efficiency and a weak current-induced fluorescence quenching was achieved. This could be explained by the fact that an interlayer of Ag_2O//MoO_x provided a stepped energy level which greatly facilitated hole injection and hence enhanced injection current. The result is verified by using the J―V curves of ‘only’ devices and further explained with the help of Fowler-Nordheim (F-N) tunneling theory.
PREPARATION OF SiO2 HIERARCHICAL NANOSTRUCTURE VIA CATALYST-FREE THERMAL EVAPORATION METHOD
JUN MA,GONG-YI LI,Xiao-dong Li,GANG PENG,YI-HE LI,HUA-YU CHEN 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2013 NANO Vol.8 No.4
A novel hierarchical nanostructure of SiO2 nanowires standing on SiO2 microwires was synthesized through a catalyst-free thermal evaporation method in nitrogen atmosphere. The SiO2 nanowires have an average diameter of 100 nm and length of 2 μm, while the diameter of the SiO2 microwires is around 10 μm and the length is hundreds of micrometers. The photoluminescence spectrum of the SiO2 hierarchical nanostructure shows stable blue and green emission at 442 nm and 533 nm, respectively. An oxygen-assisted three-step growth mechanism was suggested to interpret the growth of the SiO2 hierarchical nanostructure.
( Jun Yao ),( Qing Na Kong ),( Hua Yue Zhu ),( Zhen Zhang ),( Yu Yang Long ),( Dong Sheng Shen ) 한국화학공학회 2015 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.53 No.4
The adsorption characteristics of ammonia on MSWI bottom ash were investigated. The effect of the variation of the landfill environmental parameters including pH, anions and organic matter on the adsorption process was discussed. Results showed that the adsorption could be well described by pseudo-second-order kinetics and Langmuir model, with a maximum adsorption capacity of 156.2 mg/g. The optimum adsorption of ammonia was observed when the pH was 6.0. High level of ion and organic matter could restrict the adsorption to a low level. The above results suggested that MSWI bottom ash could affect the migration of ammonia in the landfill, which is related to the variation of the landfill circumstance.