• Title/Summary/Keyword: nano.bio fusion

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Aggregation of Laser-Generated Gold Nanoparticles Mediated by Formalin

  • Alauddin, Md.;Kim, Kuk Ki;Roy, Madhusudan;Song, Jae Kyu;Kim, Myung Soo;Park, Seung Min
    • Bulletin of the Korean Chemical Society
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    • v.34 no.1
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    • pp.188-196
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    • 2013

  • We have investigated the effects of formalin on the assembly of colloidal gold nanoparticles (AuNPs) prepared by laser ablation of a solid gold target in deionized water. Upon addition of formalin, the surface plasmon resonance (SPR) band at 519 nm for pure AuNPs decreases and shifts to red while a new broad SPR band appears at ~700 nm. The red-shift is prominent with increase in the incubation time. The average size of the initial AuNPs is around 12 nm but it increases to 23 nm after addition of formalin. It turns out that formalin acts as a cationic surfactant for AuNPs with negative surface charge in the colloidal solutions. Furthermore, through analysis of the Raman spectrum of formalin and the density functional theory calculations, we confirm that methanediol is the main species in formalin which is in charge of the aggregation of AuNPs.

  • https://doi.org/10.5012/bkcs.2013.34.1.188 인용 PDF KSCI

A Fusion Tag to Fold on: The S-Layer Protein SgsE Confers Improved Folding Kinetics to Translationally Fused Enhanced Green Fluorescent Protein

  • Ristl, Robin;Kainz, Birgit;Stadlmayr, Gerhard;Schuster, Heinrich;Pum, Dietmar;Messner, Paul;Obinger, Christian;Schaffer, Christina
    • Journal of Microbiology and Biotechnology
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    • v.22 no.9
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    • pp.1271-1278
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    • 2012

  • Genetic fusion of two proteins frequently induces beneficial effects to the proteins, such as increased solubility, besides the combination of two protein functions. Here, we study the effects of the bacterial surface layer protein SgsE from Geobacillus stearothermophilus NRS 2004/3a on the folding of a C-terminally fused enhanced green fluorescent protein (EGFP) moiety. Although GFPs are generally unable to adopt a functional confirmation in the bacterial periplasm of Escherichia coli cells, we observed periplasmic fluorescence from a chimera of a 150-amino-acid N-terminal truncation of SgsE and EGFP. Based on this finding, unfolding and refolding kinetics of different S-layer-EGFP chimeras, a maltose binding protein-EGFP chimera, and sole EGFP were monitored using green fluorescence as indicator for the folded protein state. Calculated apparent rate constants for unfolding and refolding indicated different folding pathways for EGFP depending on the fusion partner used, and a clearly stabilizing effect was observed for the SgsE_C fusion moiety. Thermal stability, as determined by differential scanning calorimetry, and unfolding equilibria were found to be independent of the fused partner. We conclude that the stabilizing effect SgsE_C exerts on EGFP is due to a reduction of degrees of freedom for folding of EGFP in the fused state.

  • https://doi.org/10.4014/jmb.1202.02023 인용 PDF KSCI