Functionality improvement of fungal lignin peroxidase by DNA shuffling for 2,4-dichlorophenol degradability and H₂O₂ stability

Ryu, K.,Hwang, S.Y.,Kim, K.H.,Kang, J.H.,Lee, E.K. Elsevier Science Publishers 2008 Journal of biotechnology Vol.133 No.1

One of the major problems of wild-type lignin peroxidase (LiP) is its inactivity at the presence of excess H<SUB>2</SUB>O<SUB>2</SUB> and high concentration of aromatic compounds. Little is known about the substrate-binding site of LiP, and functionality improvement of LiP was not actively tried by genetic engineering and directed evolution. In order to improve LiPs functionality, we performed directed evolution with a colorimetric screening method. Finally, three types of LiP mutants were screened. The catalytic efficiency of the variants toward 2,4-dichlorophenol (DCP) degradation activity and the stability against H<SUB>2</SUB>O<SUB>2</SUB> was increased over the wild type. The K<SUB>m</SUB> value of the variants toward H<SUB>2</SUB>O<SUB>2</SUB> was increased, but K<SUB>m</SUB> value toward 2,4-DCP degradation was reduced. Overall, The K<SUB>cat</SUB>/K<SUB>m</SUB> values of the mutants toward 2,4-DCP was increased ca. 4-fold, and that toward H<SUB>2</SUB>O<SUB>2</SUB> was increased ca. 89-fold. Amino acid sequence analysis indicated that the most of the mutations were located on the enzyme surface. We expect that these results coupled with recombining mutation can be successfully applied to the molecular evolution cycles for screening of LiPs and other oxidative enzymes with improved functionality and stability.

유착에 의한 AGS 및 Hep-G2 세포 표면 구조의 변화

박동규 ( D. K. Park ),전훈재 ( H. J. Chun ),박재홍 ( J. H. Park ),박철희 ( C. H. Park ),진윤태 ( Y. T. Jeen ),이홍식 ( H. S. Lee ),이상우 ( S. W. Lee ),엄순호 ( S. H. Um ),최재현 ( J. H. Choi ),김창덕 ( C. D. Kim ),류호상 ( H. S. Ryu 대한소화기학회 2002 대한소화기학회 춘계학술대회 Vol.2002 No.-

<목적> 최근 H. pylori 유착에 의한 세포 표면 구조의 변화에 관한 연구가 시도되어지고 있으나 actin 의 변화여부 및 그 특성에 관해서는 아직 명확히 정립되지 못한 실정이다. Rho GTPase는 세포 표면의 미세돌기인 microvilli, filopodia 및 membrane ruffle의 형성과 관련이 있으며, 최근 AGS 세포에서 H. pylori가 Rac activation에 의하여 membrane ruffle을 형성한다는 것과 Rac

High-Performance Blue InGaN Laser Diodes With Single-Quantum-Well Active Layers

Ryu, H.Y.,Haleem, K.H.,Lee, S.N.,Jang, T.,Son, J.K.,Paek, H.S.,Sung, Y.J.,Kim, H.K.,Kim, K.S.,O.H. Nam,Park, Y.J.,Shim, J.I. IEEE 2007 Photonics Technology Letters Vol.19 No.21

<P>The authors report on the high-performance blue laser diodes (LDs) with an emission wavelength of ~448 nm employing InGaN single-quantum-well (QW) active layers. At 100-mW continuous-wave (CW) output power, operation current and voltage are, respectively, 150 mA and 5.3 V, corresponding to the wall plug efficiency of >12%, a record value for the single-mode InGaN LDs with blue wavelengths. The single QW blue LD showed normal temperature dependence of light output-current curves with the characteristic temperature of 170 K. In addition, we demonstrate a high level of catastrophic optical damage of >300 mW and long device lifetime under CW operation condition at room temperature.</P>

Interference Effect betweenϕandΛ(1520)Production Channels in theγp→K+K−pReaction near Threshold

Ryu, S. Y.,Ahn, J. K.,Nakano, T.,Ahn, D. S.,Ajimura, S.,Akimune, H.,Asano, Y.,Chang, W. C.,Chen, J. Y.,Daté,, S.,Ejiri, H.,Fujimura, H.,Fujiwara, M.,Fukui, S.,Hasegawa, S.,Hicks, K.,Horie, K.,Ho American Physical Society 2016 Physical Review Letters Vol.116 No.23

<P>The phi-Lambda(1520) interference effect in the gamma p -> K(+)K(-)p reaction has been measured for the first time in the energy range from 1.673 to 2.173 GeV. The relative phases between phi and Lambda(1520) production amplitudes were obtained in the kinematic region where the two resonances overlap. The measurement results support strong constructive interference when K+K- pairs are observed at forward angles but destructive interference for proton emission at forward angles. Furthermore, the observed interference effect does not account for the root s = 2.1 GeV bump structure in forward differential cross sections for phi photoproduction. This fact suggests possible exotic structures such as a hidden-strangeness pentaquark state, a new Pomeron exchange, or rescattering processes via other hyperon states.</P>

Novel method for investigation of a K-Mg-based CO₂ sorbent for sorption-enhanced water-gas shift reaction

Byun, C.K.,Kwon, S.J.,Im, H.B.,Ahn, H.S.,Ryu, H.J.,Yi, K.B. Pergamon Press 2016 RENEWABLE ENERGY Vol.87 No.1

CO<SUB>2</SUB> sorption reactions at 20 bar and two different temperatures (i.e., 180 and 220 <SUP>o</SUP>C) using a K-Mg-based CO<SUB>2</SUB> sorbent were carried out in a custom-designed high-pressure thermogravimetric analyzer (pressurized bubbling fluidized bed reactor on a scale) coupled with a gas chromatograph. The experimental apparatus, including the thermogravimetric analyzer, was custom-designed to measure weight changes caused by either CO<SUB>2</SUB> sorption or water sorption or both. Analysis of the CO<SUB>2</SUB> sorption reaction revealed that water sorption takes place rapidly with a moderate CO<SUB>2</SUB> sorption rate at the early stage of the reaction. Then, the reaction migrates to CO<SUB>2</SUB> sorption with simultaneous water desorption. Therefore, the mechanism of the CO<SUB>2</SUB> sorption reaction is assumed to consist of fast hydration of K<SUB>2</SUB>CO<SUB>3</SUB> and MgO, formation and decomposition of KHCO<SUB>3</SUB>, and finally carbonation of Mg(OH)<SUB>2</SUB> resulting in MgCO<SUB>3</SUB> as the main product. K<SUB>2</SUB>CO<SUB>3</SUB> is assumed to provide an efficient pathway for CO<SUB>2</SUB> and water to travel into the core region of the sorbent via a reversible reaction between K<SUB>2</SUB>CO<SUB>3</SUB> and KHCO<SUB>3</SUB>.

ATRX induction by mutant huntingtin via Cdx2 modulates heterochromatin condensation and pathology in Huntington's disease

Lee, J,Hong, Y K,Jeon, G S,Hwang, Y J,Kim, K Y,Seong, K H,Jung, M-K,Picketts, D J,Kowall, N W,Cho, K S,Ryu, H Macmillan Publishers Limited 2012 CELL DEATH AND DIFFERENTIATION Vol.19 No.7

Aberrant chromatin remodeling is involved in the pathogenesis of Huntington's disease (HD) but the mechanism is not known. Herein, we report that mutant huntingtin (mtHtt) induces the transcription of alpha thalassemia/mental retardation X linked (ATRX), an ATPase/helicase and SWI/SNF-like chromatin remodeling protein via Cdx-2 activation. ATRX expression was elevated in both a cell line model and transgenic model of HD, and Cdx-2 occupancy of the ATRX promoter was increased in HD. Induction of ATRX expanded the size of promyelocytic leukemia nuclear body (PML-NB) and increased trimethylation of H3K9 (H3K9me3) and condensation of pericentromeric heterochromatin, while knockdown of ATRX decreased PML-NB and H3K9me3 levels. Knockdown of ATRX/dXNP improved the hatch rate of fly embryos expressing mtHtt (Q127). ATRX/dXNP overexpression exacerbated eye degeneration of eye-specific mtHtt (Q127) expressing flies. Our findings suggest that transcriptional alteration of ATRX by mtHtt is involved in pericentromeric heterochromatin condensation and contributes to the pathogenesis of HD.

InAs 양자점의 크기에 따른 분광학적 특성

권영수(Y. S. Kwon),임재영(J. Y. Leem),이철로(C. R. Lee),노삼규(S. K. Noh),유연희(Y. H. Ryu),최정우(J. W. Choe),김성만(S. M. Kim),이욱현(U. H. Lee),류동현(D. H. Ryu),이동한(D. H. Lee),박장환(Jang-Hwan Park) 한국진공학회(ASCT) 1999 Applied Science and Convergence Technology Vol.8 No.4(1)

MBE(Molecular Beam Epitaxy) 방법으로 InAS 양자점의 크기를 달리하여 성장한 lnAs 양자점의 구조적 특성과 분광학적 특성을 조사하였다. 구조적 특성은 AFM(Atomic Force Microscopy)으로 하였으며, 광학적 특성은 PL(Photoluminescence)로 수행하였다. AFM 측정결과 양자점의 밀도는 2 ML에서 최대 값인 1.1×10¹¹/㎠이다. 양자점의 크기가 증가함에 따라 PL 피크는 적색편이를 하고 있었다. 발광피크의 온도의존성을 조사한 결과 온도의 증가에 따라 발광피크는 낮은 에너지로 이동하였으며, 20 K에서 180 K 구간에서는 발광피크의 FWHM(Full Width at Half Maximum) 값은 감소하였으며, 180 K 이상의 온도에서는 온도의 증가에 따라 FWHM도 증가하였다. 한편 Arrehenius-type function으로 구한 활성화 에너지는 InAs 양자점의 크기가 증가함에 따라 증가하였다. We present Photoluminescence (PL) and Atomic Force Microscopy (AFM) image on InAs quantum dots (QDs) having different size which grown by Molecular Beam Epitaxy (MBE). For different size QDs, analysis of the AFM profiles show that the density of QDs was the maximum value (1.1×10¹¹/㎠) at 2.0 ML. In the PL spectra of QDs, it is found that the peak energy decreases with increasing dot size due to the effect of quantum confinement. Temperature dependence of PL intensities show that the PL is quenching and Red shift as the temperature increase. The FWHM range of 20 K~80 K is narrowing with increasing temperature. When temperature is over 180 K, the line-width starts to increase with increasing temperature. At last, temperature dependence of the integrated intensities were fit using the Arrehenius-type function for the activation energy. Fit value of the activation energy was increased with increasing QDs-size.

Effect of additives on redox behavior of iron oxide for chemical hydrogen storage

Ryu, J.C.,Lee, D.H.,Kang, K.S.,Park, C.S.,Kim, J.W.,Kim, Y.H. Korean Society of Industrial and Engineering Chemi 2008 Journal of industrial and engineering chemistry Vol.14 No.2

The redox behaviors of iron oxides, which were modified with Pd, Pt, Rh, Ru, Al, Ce, Ti and Zr as additives, were investigated using temperature-programmed reaction (TPR) technique. The modified iron oxides were prepared by co-precipitation method using urea precipitant. The role of additives was also examined using XRD and SEM analysis in detail. As a result, Pd, Pt, Rh and Ru additives have an effect on promoting the reduction and lowering the re-oxidation temperature of iron oxide. Especially, it is revealed that the effect of Rh species on lowering the reduction temperature is attributed to decrease of activation energy for H<SUB>2</SUB> reduction according to Fe<SUB>2</SUB>O<SUB>3</SUB>->Fe<SUB>3</SUB>O<SUB>4</SUB> course. Meanwhile, Al, Ce, Ti and Zr additives played an important role in prevention of deactivation of iron oxide by repeated redox cycles. Redox performances of iron oxides were also enhanced due to cooperative effects by co-addition of Rh and another species such as Al, Ce and Zr. Finally, Fe-O/(Rh, Ce, Zr) sample exhibited good performance for H<SUB>2</SUB> evolution by water-splitting through synergistic effect of component additives.

멜라토닌의 주사와 점등체계가 육계의 생산성 및 면역성에 미치는 영향

류명선,김상호,류경선 한국동물자원과학회 2001 한국축산학회지 Vol.43 No.5

These studies were conducted to evaluate the effects of different photoperiods on performance and immunity of broiler chicks and investigate if its immunomodulation effects were due to the melatonin or not. In experiment 1, two hundred eighty eight one-day-old commercial broiler chicks were placed into floor pen between constant lighting(CL) and intermittent lighting(IL, 1h light : 3h darkness) for 6 weeks. Weight gain, feed intake and feed conversion ratio were weekly examined. Lymphocyte activities, antibody response to Newcastle disease virus vaccine(NDV) and sheep red blood cell(SRBC) and IgG concentration were measured at the end of experiment. Changes of melatonin level were measured at 5 weeks in sera. In experiment 2, one hundred ninety two two-week-old male broiler chicks were subcutaneously injected with 0.1㎖ melatonin for 3 weeks. Lymphocyte activities, antibody response to NDV and SRBC, IgG and melatonin concentration were measured at 5 wk of age. In experiment 1, Chicks illuminated IL showed significantly higher body weight and lowest feed conversion ratio than CL treatments at 7 wk of age(P$lt;0.05). Melatonin concentration changed by dark-light cycle. Lymphocyte activity of chickens illuminated IL was significantly higher compared to That of CL treatments(P$lt;0.05). In experiment 2, increasement of antibody response to SRBC and lymphocyte activity were also observed. As the result, IL treatment improved performance and immunity of broiler chicks and affected melatonin concentration in sera. Blood melatonin were also related with melatonin injection. This results indicated that melatonin may have a role in immunomodulation in broiler chicks. The results of these experiments showed that antibody response to SRBC and total IgG concentration was enhanced by different photoperiod and melatonin treatments.

Cavity-length dependent thermal characteristics of InGaN blue laser diodes

Ryu, H.Y.,Ha, K.H. IET 2009 Electronics letters Vol.45 No.3

<P>Thermal characteristics of InGaN-based blue laser diodes (LDs) emitting around 450 nm are investigated with varying cavity length of the LDs. Characteristic temperature, junction temperature, and thermal resistance are measured for the cavity length from 650 to 1450 m. It is found that the characteristic temperature increases slowly with cavity length, and the thermal resistance is significantly improved from 30 W to 17 K/W as the cavity length increases length from 650 to 1450 m.</P>