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Lee, Saeyoung,Kim, Kyoung Heon,Kim, Hye-Yeon,Choi, In-Geol Elsevier 2017 Biochemical and biophysical research communication Vol. No.
<P><B>Abstract</B></P> <P>3,6-Anydro-<SMALL>L</SMALL>-galatonate cycloisomerase (ACI) catalyzes the cycloisomerization of a 3,6-anhydro-<SMALL>L</SMALL>-galactonic acid known as a novel metabolite in agarolytic bacteria. Here, we present 3-D structures of ACI from <I>Vibrio</I> sp. strain EJY3 (<I>Vej</I>ACI) in native and mutant forms at 2.2 Å and 2.6 Å resolutions, respectively. The enzyme belongs to the mandelate racemase subgroup of the enolase superfamily catalyzing common β-elimination reactions by α-carbon deprotonation of substrates. The structure of <I>Vej</I>ACI revealed a notable 20s loop region in the capping domain, which can be a highly conserved structural motif in ACI homologs of agar metabolism. By comparing mutant (m<I>Vej</I>AC/H300 N) and native <I>Vej</I>ACI structures, we identified a conformational change of Ile142 in <I>Vej</I>ACI that causes spatial expansion in the binding pocket. These observations imply that Ile142 and the 20s loop play important roles in enzymatic reactivity and substrate specificity. The structural phylogenetic analysis of the enolase superfamily including ACIs revealed sequential, structural, and functional relationships related to the emergence of novel substrate specificity.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The 3D-structures of a key anhydro-sugar metabolic enzyme in native and mutant forms. </LI> <LI> A conformational change of Ile142 makes a spatial expansion of the active site. </LI> <LI> The 20s loop region is a critical structural motif for substrate specificity. </LI> <LI> The reaction mechanism is proposed by critical residues in the binding pocket. </LI> </UL> </P>
Hoon Lee,Saeyoung Ahn,Changwon Lee,Hongbae Kim,Jein Jeong,Taigun Im 한국물리학회 2004 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.44 No.52
Platinum (Pt) is a biocompatible material which exhibits strong thermal and electrical conductivity due to its high melting point and good durability. Thus, it is used commonly in bio-electrodes and bio-chips. In this study, a tungsten (W) wire was coated with a platinum lm and was analyzed for its mechanical and biocompatibility properties. The platinum lm was deposited by magnetron sputtering with an UnBalanced Magnetic (UBM) eld system. The experiment was performed under a variety of conditions by changing the deposition temperature, the bias voltage, the magnetic eld and the deposition time in order to deduce the optimum conditions. We examined the exfoliation and the sedimentation states of the anode and the cathode by using microscope and an electron probe microanalysis (EPMA) for the electro-chemical corrosion test using the Hank's solution. The lm showed a very low impurity level, and the surface and the cross section of the lm appeared elaborate. No sedimentation appeared in the lm, and the crystallization in the (110), the (200), the (220) and the (222) directions observed. However, at a high current density (800 mA/cm2), sedimentation was observed in the corrosion test.
Comparison of human first and third trimester placental mesenchymal stem cell.
Park, Saeyoung,Koh, Seong-Eun,Hur, Chang Young,Lee, Won-Don,Lim, Jinho,Lee, Young-Jay Published for the International Federation for Cel 2013 Cell biology international Vol.37 No.3
<P>Placenta mesenchymal stem cells (PMSCs) have the characteristic features of stem cells including renewability in vitro, surface expression, differentiation potency and ability to adhere to the culture surface. PMSCs expressed genes are normally found in the embryonic tissues before the onset of gastrulation, indicating multipotency. However, the stemness can depend on the stages of the placenta from which the cells were isolated. PMSCs were isolated from two different stages of placenta for comparison, that is the first and third trimesters. Both sets had very similar patterns of surface expression as CD44, CD73, CD90 and CD105, and of self renewability in vitro. Expressions of pluripotency-coupled genes were also confirmed in both sets of cells; however, there was a significant difference in the expression levels: fPMSC (mesenchymal stem cells isolated from the first trimester human placenta) being 2-11-fold higher than tPMSC (mesenchymal stem cells isolated from the third trimester human placenta). Possibly due to the difference in the expression levels of the pluripotency-related genes, induction of genes specific to the ectodermal tissues were more prominent in fPMSC than tPMSC after induced differentiation.</P>
Structural insights into the psychrophilic germinal protease PaGPR and its autoinhibitory loop
Chang Woo Lee,Saeyoung Lee,Chang-Sook Jeong,Jisub Hwang,Jeong Ho Chang,In-Geol Choi,T. Doohun Kim,HaJeung Park,Hye-Yeon Kim,Jun Hyuck Lee 한국미생물학회 2020 The journal of microbiology Vol.58 No.9
In spore forming microbes, germination protease (GPR) plays a key role in the initiation of the germination process. A critical step during germination is the degradation of small acidsoluble proteins (SASPs), which protect spore DNA from external stresses (UV, heat, low temperature, etc.). Inactive zymogen GPR can be activated by autoprocessing of the N-terminal pro-sequence domain. Activated GPR initiates the degradation of SASPs; however, the detailed mechanisms underlying the activation, catalysis, regulation, and substrate recognition of GPR remain elusive. In this study, we determined the crystal structure of GPR from Paenisporosarcina sp. TG-20 (PaGPR) in its inactive form at a resolution of 2.5 Å. Structural analysis showed that the active site of PaGPR is sterically occluded by an inhibitory loop region (residues 202–216). The N-terminal region interacts directly with the self-inhibitory loop region, suggesting that the removal of the N-terminal pro-sequence induces conformational changes, which lead to the release of the self-inhibitory loop region from the active site. In addition, comparative sequence and structural analyses revealed that PaGPR contains two highly conserved Asp residues (D123 and D182) in the active site, similar to the putative aspartic acid protease GPR from Bacillus megaterium. The catalytic domain structure of PaGPR also shares similarities with the sequentially non-homologous proteins HycI and HybD. HycI and HybD are metalloproteases that also contain two Asp (or Glu) residues in their active site, playing a role in metal binding. In summary, our results provide useful insights into the activation process of PaGPR and its active conformation.
An Expansin-Like Protein from Hahella chejuensis Binds Cellulose and Enhances Cellulase Activity
Hee Jin Lee,Saeyoung Lee,고혁진,김경헌,최인걸 한국분자세포생물학회 2010 Molecules and cells Vol.29 No.4
Molecular function of the expansin superfamily has been highlighted for cellulosic biomass conversion. In this re-port, we identified a new bacterial expansin subfamily by analysis of related bacterial sequences and biochemically examined a member of this new subfamily from Hahella chejuensis (HcEXLX2). Among the various complex poly-saccharides tested, HcEXLX2 bound most efficiently to cellulose. The relative binding constant (Kr) against Avicel was 2.1 L g-1 at pH 6.0 and 4C. HcEXLX2 enhanced the activity of cellulase, producing about 4.6 times more hy-drolysis product after a 36 h reaction relative to when only cellulase was used. The extension strength test on filter paper indicated that HcEXLX2 has a texture loosening effect on filter paper, which was 53% of that observed for 8 M urea treatment. These activities, compared with a cellu-lose binding domain from Clostridium thermocellum, im-plied that the synergistic effect of HcEXLX2 comes from not only binding to cellulose but also disrupting the hy-drogen bonds in cellulose. Based on these results, we suggest that the new bacterial expansin subfamily func-tions by binding to cell wall polysaccharides and increas-ing the accessibility of cell wall degrading enzymes.