• Polymer(Korea)
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• v.25 no.5
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• pp.671-678
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• 2001

Sodium and zinc salts of poly(ethyaene-co-methacrylic acid) ionomers consist of three phases, i.e. ionic aggregates, amorphous, and crystalline phases. Dye molecules after soaked from the methanol solution are located near the amorphous phase or ionic aggregates within ionomer films. Depending on the location of the molecules in the ionomer film, they are under influence of dispersion forces (ethylene parts), polar forces (acid parts). and ionic dipole (ionic aggregates) interactions. The UV/Vis absorption peak of Nile Red under the dispersion force is found at near 500 nm, for the dye under the polar force effect 525 nm, and 550 and 610 nm for the dyes under $Na^+$ and $Zn^{2+}$ ionization effects, respectively. Since the divalent $Zn^{2+}$ ion has larger ionic dipole than the monovalent $Na^+$ ion, the larger red-shift of the absorption band due to the ionic dipole interaction is observed for $Zn^{2+}$ counter ion.

• Journal of Korean Neurosurgical Society
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• v.59 no.6
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• pp.544-550
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• 2016

Objective : Cerebral endothelial cells have unique biological features and are fascinating candidate cells for stroke therapy. Methods : In order to understand the molecular mechanisms of human cerebral endothelial cell (hCMEC/D3) transplantation in a rat stroke model, we performed proteomic analysis using 2-dimensional electrophoresis and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Protein expression was confirmed by quantitative real-time PCR and Western blot. Results : Several protein spots were identified by gel electrophoresis in the sham, cerebral ischemia (CI), and CI with hCMEC/D3 treatment cerebral ischemia with cell transplantation (CT) groups, and we identified 14 differentially expressed proteins in the CT group. Proteins involved in mitochondrial dysfunction (paraplegin matrix AAA peptidase subunit, SPG7), neuroinflammation (peroxiredoxin 6, PRDX6), and neuronal death (zinc finger protein 90, ZFP90) were markedly reduced in the CT group compared with the CI group. The expression of chloride intracellular channel 4 proteins involved in post-ischemic vasculogenesis was significantly decreased in the CI group but comparable to sham in the CT group. Conclusion : These results contribute to our understanding of the early phase processes that follow cerebral endothelial cell treatment in CI. Moreover, some of the identified proteins may present promising new targets for stroke therapy.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.263-263
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• 2013

This work examines the dynamic properties of ice surfaces in vacuum for the temperature range of 140~180 K, which extends over the onset temperatures for ice sublimation and the phase transition from amorphous to crystallization ice. In particular, the study focuses on the transport processes of excess protons and chloride ions in ice and their segregative behavior to the ice surface. These phenomena were studied by conducting experiments with a relatively thick (~100 BL) ice film constructed with a bottom $H_2O$ layer and an upper $D_2O$ layer, with excess hydronium and chloride ions trapped at the $H_2O$/$D_2O$ interface as they were generated by the ionization of hydrogen chloride. The migration of protons, chloride ions, and water molecules to the ice film surface and their H/D exchange reactions were measured as a function of temperature using the methods of low energy sputtering (LES) and Cs+ reactive ion scattering (RIS). Temperature programmed desorption (TPD) experiments monitored the desorption of water and hydrogen chloride from the surface. Our observations indicated that both hydronium and chloride ions migrated from the interfacial layer to segregate to the surface at high temperature. Hydrogen chloride gas desorbs via recombination reaction of hydronium and chloride ions floating on the surface. Surface segregation of these species is driven by thermodynamic potential gradient present near the ice surface, whereas in the bulk, their transport is facilitated by thermal diffusion process. The finding suggests that chlorine activation reactions of hydrogen chloride for polar stratospheric ice particles occur at the surface of ice within a depth of at most a few molecular layers, rather than in the bulk phase.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.62 no.1
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• pp.40-50
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• 2017

Seed storage proteins are used as carbon and nitrogen sources for the nutritional improvement of seeds. Since the composition of proteins from the Korean cultivars of proso millet is unknown, this study was conducted to obtain a reference map of millet seed proteins and identify the functional characteristics of the identified proteins. Proteins extracted from proso millet seeds of various cultivars were investigated using proteomic techniques such as 2-D electrophoresis coupled with mass fingerprinting; 1152 (differentially expressed) protein spots were detected on the 2-D gels. Among them, 26 reproducible protein spots were analyzed using matrix-assisted laser desorption/ionization time-of-flight/time-of-flight mass spectrometry. Out of the 26 proteins, 2 proteins were upregulated in all the millet cultivars, while 13 proteins were upregulated and 11 proteins were downregulated in 2 cultivars. Abundance of most of the identified protein species associated with polysaccharide and starch metabolism, transcription, and pathogenesis was significantly enhanced, while that of other protein species involved in glycolysis, stress response, and transduction was severely reduced. Taken together, the results suggest that the differential expression of the proteins from the four millet cultivars may be cultivar-specific. By conducting a proteomic investigation of millet seeds from different cultivars, we sought to better understand the functional categorization of individual proteins on the basis of their molecular functions. We believe that the identified proteins may help in investigating genetic variations in millet cultivars.

• Journal of Microbiology and Biotechnology
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• v.18 no.6
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• pp.1081-1089
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• 2008

A novel ginsenoside-hydrolyzing ${\beta}$-glucosidase was purified from Paecilomyces Bainier sp. 229 by a combination of Q-Sepharose FF, phenyl-Sepharose CL-4B, and CHT ceramic hydroxyapatite column chromatography. The purified enzyme was a monomeric protein with a molecular mass estimated to be 115 kDa. The optimal enzyme activity was observed at pH 3.5 and $60^{\circ}C$. It was highly stable within pH 3-9 and at temperatures lower than $55^{\circ}C$. The enzyme was specific to ${\beta}$-glucoside. The order of enzyme activities against different types of ${\beta}$-glucosidic linkages was ${\beta}$-(1-6)>${\beta}$-(1-2)>${\beta}$-(1-4). The enzyme converted ginsenoside Rb1 to CK specifically and efficiently. An 84.3% amount of ginsenoside Rb1, with an initial concentration of 2 mM, was converted into CK in 24 h by the enzyme at $45^{\circ}C$ and pH 3.5. The hydrolysis pathway of ginsenoside Rb1 by the enzyme was $Rb1{\to}Rd{\to}F2{\to}CK$. Five tryptic peptide fragments of the enzyme were identified by a newly developed de novo sequencing method of post-source decay (PSD) matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. By comparing the five identified peptide sequences with the NCBI database, this purified ${\beta}$-glucosidase proves to be a new protein that has not been reported before.

• Journal of Microbiology and Biotechnology
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• v.26 no.10
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• pp.1790-1799
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• 2016

Matrix assisted laser desorption ionization (MALDI)-time of flight/mass spectrometry (TOF/MS) was applied to investigate alterations in phospholipids in mitophagic cancer cells. Several phospholipids, including phosphatidylcholines (PCs), sphingomyelins (SMs), and phosphatidylinositols (PIs), were successfully analyzed in control and mitophagy-induced H460 cells in the positive and negative ion modes. Principal component analysis was applied to differentiate the two groups. The upregulated and downregulated phospholipid species in the mitophagic cells were also represented in a heatmap. In the volcano plot (fold change > 1.3 and p value < 0.01), individual species of seven PCs, two SMs, and three PIs were selected as differentially regulated phospholipids. In particular, almost all the molecular species of PC, SM, and PI were downregulated in the mitophagic cells. Quantification of these lipids indicated that mitophagy induces altered metabolism of phospholipids. Therefore, phospholipid alterations during the mitophagic process of lung cancer cells were well characterized by MALDI-TOF/MS.

• Journal of Microbiology and Biotechnology
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• v.30 no.4
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• pp.561-570
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• 2020

This study was designed to synthesize triglycerol monolaurate (TGML) with Lipozyme 435 as the catalyst, and explore its effects on the growth of Aspergillus parasiticus (A. parasiticus) and Aspergillus flavus (A. flavus) and the secretion of aflatoxin b1. The highest content of TGML (49.76%) was obtained at a molar ratio of triglycerol to lauric acid of 1.08, a reaction temperature of 84.93℃, a reaction time of 6 h and an enzyme dosage of 1.32%. After purification by molecular distillation combined with the washes with ethyl acetate and water, the purity of TGML reached 98.3%. Through characterization by electrospray-ionization mass spectrometry, infrared spectrum and nuclear magnetic resonance, the structure of TGML was identified as a linear triglycerol combined with lauroyl at the end. Finally, the inhibitory effects of TGML on the growths of A. parasiticus and A. flavus and the secretion of aflatoxin b1 were evaluated by measuring the colony diameter, the inhibition rate of mycelial growth and the content of mycotoxin in the media. The results indicated that TGML had a stronger inhibitory effects on colony growth and mycelial development of both toxic molds compared to sodium benzoate and potassium sorbate, and the secretions of toxins from A. parasiticus and A. flavus were completely suppressed when adding TGML at 10 and 5 mM, respectively. Based on the above results, TGML may be used as a substitute for traditional antifungal agents in the food industry.

• Journal of Microbiology and Biotechnology
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• v.16 no.6
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• pp.946-951
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• 2006

To study the effect of iron on Saccharomyces cerevisiae, whole-cell proteins of Saccharomyces cerevisiae were extracted and subjected to two-dimensional polyacrylamide gel electrophoresis (2D-PAGE), and differentially expressed proteins were identified. The proteins separated were further identified by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry and were compared with a protein database. Of more than 300 spots separated by molecular weight and isoelectric points, 27 differentially expressed spots were identified. Ten proteins were found to be differentially expressed at high iron concentration. Triosephosphate isomerase (TPI), YDR533C hypothetical protein, superoxide dismutase (SOD), 60 kDa heat-shock protein (HSP60), pyruvate dehydrogenase beta subunit 1 (PDB1), and old yellow enzyme 2 (OYE2) were upregulated, whereas thiol-specific antioxidant (TSA), regulatory particle non-ATPase subunit 8 (RPN8), thiol-specific peroxiredoxin 1 (AHP1), and fructose-1, 6-bisphosphate adolase (FBA) were downregulated by iron. Based on the result, we propose that SOD upregulated by iron would protect the yeast from oxidative stress by iron, and that TSA downregulated by iron would render cells hypersensitive to oxidative stress.

• Biomedical Science Letters
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• v.12 no.4
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• pp.419-425
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• 2006

Phospholipase $C-{\gamma}1\;(PLC-{\gamma}1)$ is an important signaling molecule for cell proliferation and differentiation. $PLC-{\gamma}1$ contains two pleckstrin homology (PH) domains, which are responsible for protein-protein interaction and protein-lipid interaction. $PLC-{\gamma}1$ also has two Src homology (SH)2 domains and a SH3 domain, which are responsible for protein- protein interaction. To identity proteins that specifically binds to PH domain of $PLC-{\gamma}1$, we prepared and incubated the glutathione S-transferase(GST)-fused PH domains of $PLC-{\gamma}1$ with COS7 cell lysate. We found that 90 kDa protein specifically binds to PH domain of $PLC-{\gamma}1$. By matrix-assisted laser desorption ionization time of flight-mass spectrometry, the 90 kDa protein revealed to be heat shock protein (Hsp) $90{\beta}$. Hsp $90{\beta}$ is a molecular chaperone that stabilizes and facilitates the folding of proteins that are involved in cell signaling, including receptors for steroids hormones and a variety of protein kinases. To know whether Hsp $90{\beta}$ affects on $PLC-{\gamma}1$ activity, we performed $PIP_2$ hydrolyzing activity of $PLC-{\gamma}1$ in the presence of purified Hsp $90{\beta}$ in vitro. Our results show that the Hsp $90{\beta}$ dose-dependently inhibits the enzymatic activity of $PLC-{\gamma}1$ and further suggest that Hsp $90{\beta}$ regulates cell growth and differentiation via regulation of $PLC-{\gamma}1$ activity.

• BMB Reports
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• v.38 no.5
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• pp.545-549
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• 2005

Acidithiobacillus ferrooxidans is one of the most important bacterium used in bioleaching, and can utilize $Fe^{2+}$ or sulphide as energy source. Growth curves for Acidithiobacillus ferrooxidans under phosphate starvation and normal condition have been tested, showing lag, logarithmic, stationary and aging phases as seen in other bacteria. The logarithmic phases were from 10 to 32 hours for Acidithiobacillus ferrooxidans cultivated with normal cultivating condition and from 20 to 60 hrs for Acidithiobacillus ferrooxidans cultivated phosphate starvation. Differences of protein patterns of Acidithiobacillus ferrooxidans growing in case of normal or phosphate starvation were separately investigated after cultivation at $30^{\circ}C$ by the analysis of two-dimensional gel electrophoresis (2-DE), matrix-assisted laser desorption/ionization (MALDI)-Mass spectrometry. There were total 6 protein spots identified, which were Recombination protein recA, RNA helicase, AP2 domain-containing transcription factor, NADH dehydrogenase I chain D, Hyothetical protein PF1669, and Transaldolase STY3758. From the 6 identified protein spots, 3 proteins were found to be decreased in expression at the cultivating condition of phosphate starvation, while another three upregulated.