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Lee S.,Sungkyunkwan University | Jang H.-J.,Sungkyunkwan University | Jang H.Y.,Sungkyunkwan University | Hong S.,Sungkyunkwan University | And 2 more authors.
Nanoscale | Year: 2016

We report a facile method to synthesize elongated nanoframes consisting of Pt and Au in solution. Pentagonal Au nanorods served as templates and successfully led to an elongated AuPt nanoframe after etching the core Au. Subsequently, the coating of Au around Pt ridges resulted in Pt@Au metal nanoframes. The resulting elongated nanostructure exhibited 5 well-defined ridges continuously connected along the long axis. During the shape evolution from pure Au nanorods to elongated Pt@Au metal nanoframes, their corresponding localized surface plasmon resonance bands were monitored. Especially, unique surface plasmon features were observed for elongated Pt@Au nanoframes where the short-axis oscillation of surface free electrons is strongly coupled but the long-axis oscillation is not coupled among the ridges. © The Royal Society of Chemistry 2016. Source

Lee J.H.,Korea Polar Research Institute | Lee J.H.,Korean University of Science and Technology | Park A.K.,Korea University | Do H.,Korea Polar Research Institute | And 7 more authors.
Journal of Biological Chemistry | Year: 2012

Arctic yeast Leucosporidium sp. produces a glycosylated ice-binding protein (LeIBP) with a molecular mass of ∼25 kDa, which can lower the freezing point below the melting point once it binds to ice. LeIBP is a member of a large class of ice-binding proteins, the structures of which are unknown. Here, we report the crystal structures of non-glycosylated LeIBP and glycosylated LeIBP at 1.57- and 2.43-Å resolution, respectively. Structural analysis of the LeIBPs revealed a dimeric right-handed β-helix fold, which is composed of three parts: a large coiled structural domain, a long helix region (residues 96-115 form a long α-helix that packs along one face of the β-helix), and a C-terminal hydrophobic loop region (243PFVPAPEVV 251). Unexpectedly, the C-terminal hydrophobic loop region has an extended conformation pointing away from the body of the coiled structural domain and forms intertwined dimer interactions. In addition, structural analysis of glycosylated LeIBP with sugar moieties attached to Asn185 provides a basis for interpreting previous biochemical analyses as well as the increased stability and secretion of glycosylated LeIBP. We also determined that the aligned Thr/Ser/Ala residues are critical for ice binding within the B face of LeIBP using site-directed mutagenesis. Although LeIBP has a common β-helical fold similar to that of canonical hyperactive antifreeze proteins, the ice-binding site is more complex and does not have a simple ice-binding motif. In conclusion, we could identify the ice-binding site of LeIBP and discuss differences in the ice-binding modes compared with other known antifreeze proteins and ice-binding proteins. © 2012 by The American Society for Biochemistry and Molecular Biology, Inc. Source

Lee J.,Hanyang University | Moh S.-H.,Anti aging Research Institute of BIO FDandC Co. | Ryou C.,Hanyang University | Kim D.-H.,Hanyang University
Korean Journal of Microbiology and Biotechnology | Year: 2015

Prions are proteinaceous infectious particles that cause neurodegenerative diseases, such as scrapie in sheep, bovine spongiform encephalopathy in cattle and Creutzfeldt-Jakob disease (CJD) in humans. Although the detailed process, regarding the abnormal conversion of prion proteins (PrP), remains to be fully elucidated, a number of environmental factors appear to affect the formation of misfolded PrP, termed PrPSc. Because oceanic algae contain mycosporine-like amino acids (MAAs), which exhibit cellular defensive activities under a variety of stress conditions, we investigated the level of PrPSc in prion-infected neuroblastoma cells using mycosporine-glycine, porphyra-334 and shinorine. When judged by the level of protease-resistant PrPSc in western blots, porphyra-334 and shinorine increased the level of PrPSc in cells, but mycosporine-glycine did not. The current results indicate that the MAAs tested in this study enhance the formation of PrPSc. © 2015, The Korean Society for Microbiology and Biotechnology. Source

Rastogi R.P.,Incheon National University | Sinha R.P.,Banaras Hindu University | Moh S.H.,Anti aging Research Institute of BIO FDandC Co. | Lee T.K.,Korea Advanced Institute of Science and Technology | And 7 more authors.
Journal of Photochemistry and Photobiology B: Biology | Year: 2014

Cyanobacteria are the dominant photosynthetic prokaryotes from an ecological, economical, or evolutionary perspective, and depend on solar energy to conduct their normal life processes. However, the marked increase in solar ultraviolet radiation (UVR) caused by the continuous depletion of the stratospheric ozone shield has fueled serious concerns about the ecological consequences for all living organisms, including cyanobacteria. UV-B radiation can damage cellular DNA and several physiological and biochemical processes in cyanobacterial cells, either directly, through its interaction with certain biomolecules that absorb in the UV range, or indirectly, with the oxidative stress exerted by reactive oxygen species. However, cyanobacteria have a long history of survival on Earth, and they predate the existence of the present ozone shield. To withstand the detrimental effects of solar UVR, these prokaryotes have evolved several lines of defense and various tolerance mechanisms, including avoidance, antioxidant production, DNA repair, protein resynthesis, programmed cell death, and the synthesis of UV-absorbing/screening compounds, such as mycosporine-like amino acids (MAAs) and scytonemin. This study critically reviews the current information on the effects of UVR on several physiological and biochemical processes of cyanobacteria and the various tolerance mechanisms they have developed. Genomic insights into the biosynthesis of MAAs and scytonemin and recent advances in our understanding of the roles of exopolysaccharides and heat shock proteins in photoprotection are also discussed. ©2014 Elsevier B.V. All rights reserved. Source

Tagad C.K.,University of Pune | Kim H.U.,Sungkyunkwan University | Aiyer R.C.,University of Pune | More P.,University of Pune | And 6 more authors.
RSC Advances | Year: 2013

The paper reports a rapid and single pot synthesis of polysaccharide stabilized silver nanoparticles (Ag NPs). The ability of Ag NPs to catalyze the reduction of hydrogen peroxide (H2O2) is successfully explored for the development of an optical fiber H2O2 sensor in the concentration range of 10-2 to 10-6 M. © 2013 The Royal Society of Chemistry. Source

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