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Isolation and Structural Determination of Squalene Synthase Inhibitor from Prunus mume Fruit
( Sung Won Choi ),( Nam Yoon Hur ),( Soon Cheol Ahn ),( Dong Seob Kim ),( Jae Kwon Lee ),( Dae Ok Kim ),( Seung Kook Park ),( Byung Yong Kim ),( Moo Yeol Baik ) 한국미생물생명공학회 2007 Journal of microbiology and biotechnology Vol.17 No.12
Kwon, Min Jee,Han, Myeong Hoon,Bagley, Joshua A.,Hyeon, Do Young,Ko, Byung Su,Lee, Yun Mi,Cha, In Jun,Kim, Seung Yeol,Kim, Dong Young,Kim, Ho Min,Hwang, Daehee,Lee, Sung Bae,Jan, Yuh Nung National Academy of Sciences 2018 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.115 No.45
<P><B>Significance</B></P><P>It remains unclear how the structural properties of polyglutamine (polyQ) proteins, which underlie several neurodegenerative disorders, including Huntington’s disease and spinocerebellar ataxias (SCAs), translate into the toxicity of these proteins. Here, we demonstrate that coiled-coil structures in expanded polyQ regions of SCA type 3 (SCA3) proteins cause dendrite defects in <I>Drosophila</I> neurons, as well as behavioral abnormalities. Moreover, interactions of SCA3 with Foxo mediated by coiled-coil domains of these two proteins resulted in functional impairment of this transcription factor, whereas its overexpression significantly rescued the SCA3-induced defects. Our study expanded the current understanding of neuronal pathology mediated by polyQ proteins via the coiled-coil–mediated interactions. These results may have important implications in therapeutic strategies for polyQ protein-related diseases.</P><P>Neurodegenerative disorders, such as Huntington’s diseases and spinocerebellar ataxias (SCAs), are driven by proteins with expanded polyglutamine (polyQ) tracts. Recently, coiled-coil structures in polyQ regions of such proteins were shown to facilitate aggregate formation and ultimately lead to cell death. However, the molecular mechanism linking these structural domains to neuronal toxicity of polyQ proteins remains elusive. Here, we demonstrate that coiled-coil structures in the Q repeat region of SCA type 3 (SCA3) polyQ proteins confer protein toxicity in <I>Drosophila</I> neurons. To functionally characterize coiled-coil structures in the Q repeat regions, we generated three structural variants of SCA3 polyQ proteins: (<I>i</I>) MJDtr-76Q, containing both α-helical coiled-coil and β-sheet hairpin structures in the Q repeat region; (<I>ii</I>) MJDtr-70Q_cc0, possessing only α-helical coiled-coil structures due to the incorporation of β-sheet–breaking residues (Q-to-N or Q-to-E mutations); and (<I>iii</I>) MJDtr-70Q_pQp, with no secondary structure due to the introduced proline residues (Q-to-P mutations). Through comparative analysis of these variants, we found that coiled-coil structures facilitated nuclear localization of SCA3 polyQ proteins and induced dendrite defects in <I>Drosophila</I> dendritic arborization neurons. Furthermore, genetic and functional screening identified the transcription factor Foxo as a target of polyQ proteins, and coiled-coil–mediated interactions of Foxo and polyQ proteins in the nucleus resulted in the observed dendrite and behavioral defects in <I>Drosophila</I>. These results demonstrate that coiled-coil structures of polyQ proteins are crucial for their neuronal toxicity, which is conferred through coiled-coil to coiled-coil interactions with the nuclear targets of these proteins.</P>
Kwon, Sung-Yeol The Korean Institute of Electrical Engineers 2004 KIEE International Transactions on Electrophysics Vol.4C No.2
0-3 PbTiO$_3$/P(VDF/TrFE) nanocomposite thin films for passive pyroelectric infrared sensors were fabricated by a two-step spin coating technique. 65wt% VDF and 35 wt% TrFE was formed into a P(VDF/TrFE) powder. Nano size PbTiO$_3$ powder was used. 0-3 connectivity of PbTiO$_3$/P(VDF/TrFE) composite film was successfully achieved and observed using SEM photography. The dielectric constant and pyroelectric coefficient were measured and compared with P(VDF/TrFE). A very low dielectric constant (13.48 at 1KHz and sufficiently high pyroelectric coefficient (3.101 nC/$\textrm{cm}^2$ㆍk at 5$0^{\circ}C$) were measured. This nanocomposite can be used for a new pyroelectric infrared sensor to achieve better performance.
Evaluation of Mechanical Properties for Narrow-Gap Weld Zone in Reactor Coolant Loop
Kwon, Jae Do,Woo, Seung Wan,Lee, Choon Yeol,Kang, Suk Chull,Shin, Ho Sang Trans Tech Publications, Ltd. 2005 Key Engineering Materials Vol.297 No.-
<P>Conventionally, shield metal arc welding (SMAW) process was applied to join pipes of RCL, which caused lot of loss in time and cost due to excessive heat input and defects in joining section. Recently, narrow-gap welding (NGW) process was introduced to overcome the disadvantages of SMAW. However, the application of NGW to nuclear power plant is not yet common because safety of NGW process is not proven. In present paper, the welded coupons are manufactured under different welding processes in carbon steel. Then, microstructure observations and various mechanical tests are performed. It is verified that the mechanical properties of carbon steel are greatly changed after repair welding process due to applied heat flux, and that the effect of post-welding heat treatment is beneficial.</P>
Kwon, Sung-Yeol The Korean Institute of Electrical Engineers 2002 KIEE International Transactions on Electrophysics Vol.12C No.4
The pyroelectric sensor of P(VDF/TrFE) film as sensing materials has been fabricated and evaluated with another commercial pyroelectric sensor using ceramic materials for sensing, The device was mounted in TO-5 housing to detect infrared light of a 5.5~14 ${\mu}{\textrm}{m}$ wavelength. The NEP(noise equivalent power) and specific detectivity D* of the device were 2.13$\times$10$^{-8}$ W and 9.37 10$^{6}$ cm/W under emission energy of 13 ㎼/$\textrm{cm}^2$, respectively.
Kwon, Kihyun,Lee, Kang Yeol,Kim, Minjung,Lee, Young Wook,Heo, Jinhwa,Ahn, Sang Jung,Han, Sang Woo Elsevier 2006 Chemical physics letters Vol.432 No.1
<P><B>Graphical abstract</B></P><P>Monodisperse icosahedral gold nanoparticles with controllable size were prepared in high-yield by a seed-mediated growth approach.</P><ce:figure id='figure.0010'></ce:figure> <P><B>Abstract</B></P><P>The aqueous-phase synthesis of polyhedral gold nanoparticles with remarkably narrow size distribution is reported. By using a seeding growth approach, icosahedral gold particles with controllable size can be synthesized in high-yield. Citrate-capped 3.5nm gold nanoparticles, prepared by the reduction of HAuCl<SUB>4</SUB> with sodium borohydride, are used as seeds. The synthesized gold nanoparticles were characterized by transmission electron microscopy, scanning electron microscopy, and X-ray diffraction. The prepared gold nanoparticles show efficient surface-enhanced Raman scattering activities.</P>
Ferritin Overload Suppresses Male Fertility Via altered Acrosome Reaction
Kwon, Woo-Sung,Rahman, Md Saidur,Kim, Ye-Ji,Ryu, Do-Yeol,Kahtun, Amena,Pang, Myung-Geol The Korean Society of Animal Reproduction 2015 Reproductive & developmental biology Vol.39 No.4
Iron is required for cell viability but is toxic in excess. While the iron-mediated malfunction of testicular cells is well appreciated, the underlying mechanism(s) of this effect and its relationship with fertility are poorly understood. Ferritin is a ubiquitous intracellular protein that controls iron storage, ferroxidase activity, immune response, and stress response in cells. Ferritin light chain protein (FTL) is the light subunit of the Ferritin. Previously, we had identified the FTL in bovine spermatozoa following capacitation. In present study, to investigate the role of Ferritin in sperm function, mice spermatozoa were incubated with multiple doses (1, 10 and $100{\mu}M$) of sodium nitroprusside (SNP), an iron donor. SNP was increased Ferritin levels in a dose-dependent manner. The Ferritin was detected on the acrosome in spermatozoa by immunocytochemistry. Short-term exposure of spermatozoa to SNP increased tyrosine phosphorylation and the acrosome reaction (AR). Finally, SNP affected a significant decrease in the rate of fertilization as well as blastocyst formation during early embryonic development. On the basis of these results, we propose that the effects of Ferritin on the AR may reduce overall sperm function leads to poor fertility in males and compromised embryonic development.