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Yu, K.,Kang, S.,Park, N.,Shin, J.,Kim, Yangmee 부산대학교 유전공학연구소 2000 분자생물학 연구보 Vol.16 No.-
Mastoparan B (MP-B), an antimicrobial cationic tetradecapeptide amide isolated from the venom of the hornet Vespa basalis, is an amphiphilic x-helical peptide. MP-B possesses a mariety of biological activities, such as mast cells degradation histamine release, erythrocyte lysis and inhibition of the growth of Gram-positive and Gram-negative bacteria. In order to study the relationship between the structure and the biological activity of MP-B, we used four analogs by replacing amino acids with alanine. Tertiary structures of MP-B and its analogs in 2,2,2-trifluoroethanol (TFE)-containing aqueous solution have been determined by NMR spectroscopy and molecular modeling. The results indicate that [Ala^4]MP-B and [Ala^12]MP-B with higher hydrophobicity adopt a higher content of amphiphilic helical structures, and have better antimicrobial and hemolytic activities than MP-B. However, [Ala^3]MP-B and [Ala^9]MP-B and hydrophobicity have disordered structures. [Ala^3]MP-B and [Ala^9]MP-B have low antimicrobial activity and much less hemolytic activity relative to MP-B. It is likely that tryptophan residue in MP-B and appropriate hydrophobicity of MP-B to induce x-helical structure is essential for the antibacterial and hemolytic activity of MP-B. This study can aid understanding of the structure-activity relationship of MP-B and to design peptides to possess lytic activity.
Yu, K.,Park, K.,Kang, S.-W.,Shin, S.Y.,Hahm, K.-S.,Kim, Y. 부산대학교 유전공학연구소 2002 분자생물학 연구보 Vol.18 No.-
CRAMP was identified from a cDNA clone derived from mouse femoral marrow cells as a member of cathelicidin-derived antimicrobial peptides. This peptide shows potent antimicrobial activity against gram-positive and gram-negative bacteria but no hemolytic activity against human erythrocytes. CRAMP was known to cause rapid permeabilization of the inner membrane of Escherichia coli. In this study, the structure of CRAMP adopts a mainly x-helical conformation in TFE/H_2O solution, DPC micelles, SDS micelles and liposomes, whereas it has a random structure in aqueous solution. The tertiary structure of CRAMP in TFE/H_2O (1:1, v/v), as determined by NMR spectroscopy, consists of two amphipathic α-helices from Leu^4 to Lys^10 and from Gly^16 to Leu^33. These two helices are connected by a flexible region from Gly^11 to Gly^16. Previous analysis of series of fragments composed of various portion of CRAMP revealed that an 18-residue fragment with the sequence from Gly^16 to Leu^33 was found to retain antibacterial activity. Therefore, the amphipathic x-helical region from Gly^16 to Leu^33 of CRAMP plays important roles in spanning the lipid bilayers as well as its antibiotic activity. Based on this structure, novel antibiotic peptides having strong antibiotic activity, with no hemolytic effect will be developed.
Yu, K‐,H.,Hong, K‐,S.,Lee, B‐,C.,Oh, M‐,S.,Cho, Y‐,J.,Koo, J‐,S.,Park, J‐,M.,Bae, H‐,J.,Han, M‐,K.,Ju, Y‐,S.,Kang, D‐,W.,Appelros, P. Blackwell Publishing Ltd 2011 Acta neurologica Scandinavica Vol.123 No.5
<P>Yu K‐H, Hong K‐S, Lee B‐C, Oh M‐S, Cho Y‐J, Koo J‐S, Park J‐M, Bae H‐J, Han M‐K, Ju Y‐S, Kang D‐W, Appelros P, Norrving B, Terent A. Comparison of 90‐day case‐fatality after ischemic stroke between two different stroke outcome registries using propensity score matching analysis. Acta Neurol Scand: 2011: 123: 325–331. © 2010 John Wiley & Sons A/S.</P><P><B>Background – </B> It has not been clarified whether the disparity in ischemic stroke outcome between populations is caused by ethnic and geographic differences or by variations in case mix. Propensity score matching (PSM) analysis can overcome some analytical problems but is rarely used in stroke outcome research. This study was to compare the ischemic stroke case‐fatality between two PSM cohorts of Sweden and Korea.</P><P><B>Methods – </B> Prognostic variables related to baseline characteristics and stroke care were included in our PSM model. Then, we selected 7675 Swedish and 1220 Korean patients with ischemic stroke from each stroke registers and performed one‐to‐one matching based on propensity scores of each patient.</P><P><B>Results – </B> After PSM, all measured variables were well balanced in 1163 matched subjects, and the 90‐day case‐fatality was identical 6.2% (HR 0.997, 95%CI 0.905–1.099) in Sweden and Korea.</P><P><B>Conclusions – </B> No difference is found in the 90‐day case‐fatality in propensity score‐matched Swedish and Korean patients with ischemic stroke.</P>
Yuk, Jong Min,Seo, Hyeon Kook,Choi, Jang Wook,Lee, Jeong Yong American Chemical Society 2014 ACS NANO Vol.8 No.7
<P>Recent real-time analyses have provided invaluable information on the volume expansion of silicon (Si) nanomaterials during their electrochemical reactions with lithium ions and have thus served as useful bases for robust design of high capacity Si anodes in lithium ion batteries (LIBs). In an effort to deepen the understanding on the critical first lithiation of Si, especially in realistic liquid environments, herein, we have engaged <I>in situ</I> graphene liquid cell transmission electron microscopy (GLC-TEM). In this technique, chemical lithiation is stimulated by electron-beam irradiation, while the lithiation process is being monitored by TEM in real time. The real-time analyses informing of the changes in the dimensions and diffraction intensity indicate that the very first lithiation of Si nanoparticle shows anisotropic volume expansion favoring the ⟨110⟩ directions due to the smaller Li diffusion energy barrier at the Si–electrolyte interface along such directions. Once passing this initial volume expansion stage, however, Li diffusion rate becomes isotropic in the inner region of the Si nanoparticle. The current study suggests that the <I>in situ</I> GLC-TEM technique can be a useful tool in understanding battery reactions of various active materials, particularly those whose initial lithiation plays a pivotal role in overall electrochemical performance and structural stability of the active materials.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2014/ancac3.2014.8.issue-7/nn502779n/production/images/medium/nn-2014-02779n_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn502779n'>ACS Electronic Supporting Info</A></P>
Superstructural defects and superlattice domains in stacked graphene
Yuk, J.M.,Jeong, H.Y.,Kim, N.Y.,Park, H.J.,Kim, G.,Shin, H.S.,Ruoff, R.S.,Lee, J.Y.,Lee, Z. Pergamon Press ; Elsevier Science Ltd 2014 Carbon Vol.80 No.-
Recently there has been interest in two-dimensional graphene-based superstructures, such as twisted bilayer or trilayer graphene or graphene on hexagonal boron nitride, stacked one on top of the other. These superstructures are expected to have electronic and optical properties that depend on even small changes in the twist angles. By structural mapping in the micrometer scale, we demonstrate that superstructures consist of stacking-induced 'superlattice domains'. The rotational disorder between domains created by the superstructural defects, such as wrinkles, folds and grain boundaries, and guest species intercalated between stacked layers, was analyzed at a resolution of sub-one degree. This comprehensive approach provides crucial structural information on graphene-based superstructures.
Regulation of Schizosaccharomyces pombe Gene Encoding Copper/Zinc Superoxide Dismutase
Yuk-Young Lee,Haeng-Im Jung,박은희,Jae-Hoon Sa,Chang-Jin Lim 한국분자세포생물학회 2002 Molecules and cells Vol.14 No.1
Copper/zinc superoxide dismutase (Cu/Zn SOD) is an abundant enzyme that scavenges superoxide radicals. To independently examine the regulation of the Cu/Zn SOD gene of the fission yeast Schizosaccharomyces pombe, the 882 bp upstream region of the Cu/Zn SOD gene was fused into the promoterless b-galactosidase gene of the shuttle vector YEp357R, which generated the fusion plasmid pSC601. Cupric chloride (4.5 mM), aluminum chloride (10 mM), cadmium chloride (30 mM, 50 mM), mercuric chloride (1 mM), zinc chloride (11 mM), and hydrogen peroxide (0.3 mM) enhanced the synthesis of b-galactosidase from the fusion plas-mid. These results indicate that the expression of the S. pombe Cu/Zn SOD gene is, therefore, regulated by various metal ions, however superoxide-generating me-nadione did not affect the expression of the S. pombe Cu/Zn SOD gene. The expression of the S. pombe Cu/Zn SOD gene is also regulated by the transcription factor Pap1