• Bulletin of the Korean Chemical Society
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• v.34 no.8
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• pp.2419-2424
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• 2013

Guanosine-5'-diphosphate 3'-diphosphate (ppGpp) serves as alarmone in bacterial stringent responses. In this study, an affinity column was constructed by immobilizing ppGpp to NHS-Sepharose for isolating ppGpp-binding proteins. A novel ppGpp-binding protein, YjgA, was isolated and characterized by MALDI-TOF MS (matrix-assisted laser desorption ionization-time-of-flight mass spectrometry) coupled with two-dimensional gel electrophoresis. YjgA and truncated forms of YjgA were cloned and over-expressed in BL21 (DE3). The binding affinity of YjgA to ppGpp was determined by equilibrium dialysis. The interaction of YjgA with ppGpp was very specific, considering that the dissociation constant of YjgA with ppGpp was measured as $5.2{\pm}2.0{\mu}M$, while the affinities to GTP and GDP were about 60 and 30 times weaker than ppGpp. Expression of yjgA gene in Escherichia coli K-12 MG1655 was examined by reverse transcription polymerase chain reaction (RT-PCR). RT-PCR results revealed that yjgA was expressed from early to late stationary phase. The yjgA deletion mutant exhibited decreased cell number at stationary phase compared to parent strain and the over-expression of YjgA increased the cell number. These results suggested that YjgA might stimulate cell division under stationary phase. In most prokaryotic genome, about half of the protein candidates are hypothetical, that are expected to be expressed but there is no experimental report on their functions. The approach utilized in this study may serve as an effective mean to probe the functions of hypothetical proteins.

• Journal of the Mineralogical Society of Korea
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• v.23 no.4
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• pp.357-365
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• 2010

Optically stimulated luminescence (OSL) of quartz is commonly applied to the age dating of Quaternary sediments. However, one of the issues is that some of the quartz samples are not suitable to OSL dating. Mineralogical analysis of the quartz samples with diverse OSL signals are required to strengthen the reliability and applicability of the OSL dating. We analysed the OSL signal characteristics of sedimentary quartz samples from diverse geological environments and measured their trace element contents using laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Quartz samples could be grouped into ones suitable to OSL dating and ones unsuitable on the basis of their OSL signal characteristics. The average trace element contents ranged from 73 to 260 ppm (Al), and from 61 to 248 ppm (Ti) with minor Li, Mg, Cr, Mn, and Fe contents below 40 ppm. We did not find any significant variation of trace element contents of quartz samples consistent with their OSL signal characteristics. This indicates unknown mineralogical factors causing diverse OSL characteristics which should be confirmed by further analysis of sufficient set of samples.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.58 no.1
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• pp.50-56
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• 2013

For accurate analysis of low molecular peptides using SELDI-TOF MS (surface enhanced laser desorption/ionization time of flight mass spectrometry), the optimized analytical conditions should be established for a specific biological sample. This study was conducted to optimize SELDI-TOF MS analytical conditions for profiling low molecular peptide below 10 kDa presented in sorghum seeds. Analytical conditions were as follows; (1) protein chips: CM10 (weak cation exchanger) and Q10 (strong anion exchanger), (2) dilution factors of binding buffer: 1/2, 1/5, 1/10, 1/20, 1/50, 1/100, and 1/200, (3) the stringency of Q10 binding buffer: 10 mM and 100 mM, and (4) protein extraction buffers: sodium borate, sodium borate + acetone, phenol, and TCA buffers. Optimum dilution factors were selected as 1/20 and 1/50 in both protein chips, CM10 and Q10. Low stringency of Q10 binding buffer (10mM) detected more peptide peaks than high stringency (100 mM). Selected protein extraction buffers of sorghum seed for SELDI-TOF MS analysis was the sodium borate buffer in the range of 2~10 kDa, while the phenol buffer was more suitable in the range of 10~20 kDa.

• Radiation Oncology Journal
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• v.22 no.4
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• pp.298-306
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• 2004

Purpose: The purpose of this study was to identify Radiosensitivity of proteins in tissues with different radiosensitivity. Materials and Methods: C3H/HeJ mice were exposed to 10 Gy. The mice were sacrifiud 8 hrs after radiation. Their spleen and liver tissues were collected and analyzed histologicaly for apoptosis. The expressions of radiosusceptibillty protein were analyzed by 2-dimensional electrophoresis and matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Resilts: The Peak of apoptosis levels were $35.3{\pm}1.7{\%}$ in spleen and $0.6{\pm}0.2{\%}$ in liver at 8 hrs after radiation. Liver, radioresistant tissues, showed that the levels of ROS metabolism related to proteins such as cytochromm c, glutathione S transferase, NADH dehydrogenase, riken cDNA and peroxiredoxin Vl increased after radiation. The expression of cytochrome c increased significantly in spleen and liver tissues after radiation. In spleen, radiosensitivity tissue, the identified proteins showed a significantly quantitative alteration following radiation. It was categorized as signal transduction, apoptosis, cytokine, Ca signal related protein, stress-related protein, cytoskeletal regulation, ROS metabolism, and others. Conclusion: Differences of radiation-induced apoptosis by tissues specifted were coupled with the induction of related radiosensitivity and radioresistant proteins. The result suggests that apoptosis relate protein and redox proteins play important roles in this radiosusceptibility.

• Nuclear Engineering and Technology
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• v.52 no.12
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• pp.2860-2866
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• 2020

Oxide dispersion-strengthened materials W-1wt%Pr₂O₃ and W-1wt%La₂O₃ were synthesized by wet chemical method and spark plasma sintering. The field emission scanning electron microscopy (FE-SEM) analysis, XRD and Vickers microhardness measurements were conducted to characterize the samples. The irradiations were carried out with a 5 keV helium ion beam to fluences up to 5.0 × 10²¹ ions/m² under 600 ℃ using the low-energy ion irradiation system. Transmission electron microscopy (TEM) study was performed to investigate the microstructural evolution in W-1wt%Pr₂O₃ and W-1wt%La₂O₃. At 1.0 × 10²⁰ He⁺/m², the average loops size of the W-1wt%Pr₂O₃ was 4.3 nm, much lower than W-1wt% La₂O₃ of 8.5 nm. However, helium bubbles were not observed throughout in both doped W materials. The effects of pre-irradiation with 1.0 × 10²¹ He⁺/m² on trapping of injected deuterium in doped W was studied by thermal desorption spectrometry (TDS) technique using quadrupole mass spectrometer. Compared with the samples without He⁺ pre-irradiation, deuterium (D) retention of doped W materials increased after He⁺ irradiation, whose retention was unsaturated at the damage level of 1.0 × 10²²D₂⁺/m². The present results implied that irradiation effect of He⁺ ions must be taken into account to evaluate the deuterium retention in fusion material applications.

• Korean Journal of Environmental Biology
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• v.39 no.4
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• pp.445-451
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• 2021

In this study, we described the production of an antibody to living modified organisms (LMOs) containing the gene encoding for 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) from Agrobacterium tumefaciens strain CP4 EPSPS provides resistance to the herbicide glyphosate (N- (phosphonomethyl) glycine). These LMOs were approved and have recently been used in the feed, food production, and processing industries in South Korea. Highly efficient monoclonal antibody (mAb) production is crucial for developing assays that enable the proper detection and quantification of the CP4 EPSPS protein in LMOs. This study describes the purification and characterization of recombinant CP4 EPSPS protein in E. coli BL21 (DE3) based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and matrixassisted laser desorption/ionization time-of-flight mass spectrometry. The production of mAbs was undertaken based on the standard operating procedure of Abclon, Inc.(South Korea), and the purity of the mAbs was assessed using SDS-PAGE. The following five mAb clones were produced: 2F2, 4B9, 6C11, 10A9, and 10G9. To verify the efficiency and specificity of the five developed mAbs, we performed Western blotting analysis using the LM (living modified) cotton crude extracts. All mAbs could detect the CP4 EPSPS protein in the LM cotton traits MON1445 and MON88913 with high specificity, but not in any other LM cottons or non-LM cottons. These data indicate that these five mAbs to CP4 EPSPS could be successfully used for the further development of antibody-based detection methods to target CP4 EPSPS protein in LMOs.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.27 no.1
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• pp.15-25
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• 2024

Purpose: This study aimed to investigate the presence of autoantigens in the gastric juices of children. Methods: Gastric juice and serum samples were obtained from 53 children <15 years of age who underwent gastric endoscopy. Among these, 8, 22, and 23 participants were in the age groups 0-5, 6-10, and 11-15 years, respectively. These samples were analyzed using two-dimensional electrophoresis (2-DE), immunoblot analysis, and matrix-assisted laser desorption ionization-time of-flight mass spectrometry. Furthermore, we reviewed the histopathological findings and urease test results and compared them with the results of 2-DE and immunoblot analysis. Results: There were no statistically significant differences in urease test positivity, grades of chronic gastritis, active gastritis, or Helicobacter pylori infiltration of the antrum and body among the three age groups. Three distinct patterns of gastric juice were observed on 2-DE. Pattern I was the most common, and pattern III was not observed below the age of 5 years. Histopathological findings were significantly different among active gastritis (p=0.037) and H. pylori infiltration (p=0.060) in the gastric body. The immunoblots showed large spots at an approximate pH of 3-4 and molecular weights of 31-45 kDa. These distinct, large positive spots were identified as gastric lipase and pepsin A and C. Conclusion: Three enzymes, which are normally secreted under acidic conditions were identified as autoantigens. Further investigation of the pathophysiology and function of autoantigens in the stomach is required.

• Journal of Food Hygiene and Safety
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• v.32 no.4
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• pp.284-289
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• 2017

Oxidized polyethylene wax (OPEW) is, one of the food additives, used as a coating agent in citrus fruits and nuts. OPEW is authorized to quantum satis in EU, USA, and is acceptable less than 250 mg/kg in Australia and New Zealand. But OPEW is unauthorized as a food additive in Korea. This study was to establish the analytical method of OPEW and demonstrate the effective application of various food samples. We first conducted to compare the various analytical method including acid value (AV), high temperature gel permeation chromatography (HT-GPC), matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF/MS), gas chromatography flame ionization detector (GC-FID) and fourier transform infrared spectroscopy (FT-IR). This result indicated that FT-IR spectrum of OPEW treated food sample displayed absorption bands for carbonyl group (C=O, $1714cm^{-1}$), ester group (C-O, $1463cm^{-1}$), aliphatic group (C-H, $2916cm^{-1}$). Furthermore, IR spectrum of OPEW treated food sample showed similar tendency with IR spectrum of OPEW standard. Therefore, it is confirmed that analytical method using FT-IR can be detected on analysis of OPEW in food. As a result of monitoring of 111 samples using established analytical method, OPEW was not detected in the food samples.