• 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.

• BMB Reports
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• v.53 no.7
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• pp.349-356
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• 2020

Mass spectrometry (MS) is an ideal tool for analyzing multiple types of (bio)molecular information simultaneously in complex biological systems. In addition, MS provides structural information on targets, and can easily discriminate between true analytes and background. Therefore, imaging mass spectrometry (IMS) enables not only visualization of tissues to give positional information on targets but also allows for molecular analysis of targets by affording the molecular weights. Matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) MS is particularly effective and is generally used for IMS. However, the requirement for an organic matrix raises several limitations that get in the way of accurate and reliable images and hampers imaging of small molecules such as drugs and their metabolites. To overcome these problems, various organic matrix-free LDI IMS systems have been developed, mostly utilizing nanostructured surfaces and inorganic nanoparticles as an alternative to the organic matrix. This minireview highlights and focuses on the progress in organic matrix-free LDI IMS and briefly discusses the use of other IMS techniques such as desorption electrospray ionization, laser ablation electrospray ionization, and secondary ion mass spectrometry.

• Bulletin of the Korean Chemical Society
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• v.34 no.1
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• pp.207-210
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• 2013

We report the construction of a MALDI imaging mass spectrometer equipped with a specially designed laser focusing lens, a compact aspherical singlet lens, that obtains a high-lateral imaging resolution in the microprobe mode. The lens is specially designed to focus the ionization laser (${\lambda}$ = 355 nm) down to a $1{\mu}m$ diameter with a long working distance of 34.5 mm. With the lens being perpendicular to the sample surface and sharing the optical axis with the ion path, the imaging mass spectrometer achieved an imaging resolution of as good as $5{\mu}m$ along with a high detection sensitivity of 100 fmol for peptides. The mass resolution was about 900 (m/${\Delta}m$) in the linear TOF mode. The high-resolution capability of this instrument will provide a new research opportunity for label-free imaging studies of various samples including tissues and biochips, even for the study at a single cell level in the future.

• Korean Journal of Clinical Laboratory Science
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• v.47 no.4
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• pp.286-291
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• 2015

Equol has beneficial effects on human health. Fermented soy products contain equol, and many microbes participate in the equol production process. This study investigated fermented Korean soybean paste, doenjang. Thirty seven doenjang samples collected from different manufacturers were examined. Equol was detected in 3 samples (D2, D13, and D19) at the maximum content of 507 ng/100 g by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Fifteen microbial species were isolated and identified by 16S rRNA gene sequence analysis and by matrix assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS). Bacillus spp, Paenibacillus spp, Tetragenococcus spp, Stapylococcus spp, and Clostridium species were the predominant bacteria in equol containing doenjang samples.

• Korean Journal of Clinical Laboratory Science
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• v.50 no.3
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• pp.275-283
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• 2018

Helicobacter pylori is a causative organism of various gastrointestinal diseases, including chronic gastritis, gastric ulcer, or gastric adenocarcinoma. Pathogenic factors, such as cytotoxin-associated protein A (CagA) and vacuolating cytotoxic protein A (VacA), play a role. This study analyzed qualitatively and quantitatively the effects of zerumbone on the changes in the protein expression levels of various H. pylori proteins, including CagA and VacA. Approximately 200 significant proteins were screened for the H. pylori 60190 (VacA positive / CagA positive; Eastern type) strain, and proteomic analysis was performed on 13 protein molecules that were clinically significant. After two-dimensional electrophoresis (2-DE), $ImageMaster^{TM}$ 2-DE Platinum software was used for quantitative measurements of protein spots. Matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-TOF-MS) and liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) were used for protein identification. After intensive analysis of the proteins that showed significant changes, a reverse transcription-polymerase chain reaction was performed as required to verify the results. In this study, the significance of zerumbone as a therapeutic agent for H. pylori infection was examined by screening a new pharmacological activity mechanism of zerumbone.

• Journal of Microbiology
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• v.43 no.6
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• pp.503-509
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• 2005

The production of manganese peroxidase (MnP) by Irpex lacteus, purified to electrophoretic homogeneity by acetone precipitation, HiPrep Q and HiPrep Sephacryl S-200 chromatography, was shown to correlate with the decolorization of textile industry wastewater. The MnP was purified 11.0-fold, with an overall yield of $24.3\%$. The molecular mass of the native enzyme, as determined by gel filtration chromatography, was about 53 kDa. The enzyme was shown to have a molecular mass of 53.2 and 38.3 kDa on SDS-PAGE and MALDI-TOF mass spectrometry, respectively, and an isoelectric point of about 3.7. The enzyme was optimally active at pH 6.0 and between 30 and $40^{\circ}C$. The enzyme efficiently catalyzed the decolorization of various artificial dyes and oxidized Mn (II) to Mn (III) in the presence of $H_2O_2$. The absorption spectrum of the enzyme exhibited maxima at 407, 500, and 640 nm. The amino acid sequence of the three tryptic peptides was analyzed by ESI Q- TOF MS/MS spectrometry, and showed low similarity to those of the extracellular peroxidases of other white-rot basidiomycetes.

• Bulletin of the Korean Chemical Society
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• v.30 no.5
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• pp.1127-1130
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• 2009

The effects of different dihydroxybenzoic acid (DHB) isomers, when used as matrix materials in matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), were investigated in analyses of polyethylene glycol (PEG) polymers. PEG polymers ranging from 400 to 8,000 Da were prepared in different DHB isomer matrices using solvent-based and solvent-free methods. PEG samples were detected only in matrices of 2,3-DHB, 2,5-DHB, and 2,6-DHB while the most intense peaks were observed using 2,6-DHB in both solvent-free and solvent-based preparations.

• Mass Spectrometry Letters
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• v.12 no.3
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• pp.81-84
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• 2021

Collagen, which accounts for one-third of human protein, is reduced due to human aging, and much attention is focused on making collagen into food to prevent such aging. Gel permeation chromatography with Reflective Index (RI) detection (GPC/RI) was chosen as the most suitable instrument to confirm molecular weight distribution, and we explored the use of this technique for analysis of collagen peptide molecular sizes and distributions. Data reliability was verified by matrix-assisted laser desorption/ionization coupled to time-of-flight (MALDI-TOF) mass spectrometric analysis. The data were considered meaningful for comparative analysis of molecular weight distribution patterns.

• BMB Reports
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• v.39 no.1
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• pp.46-54
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• 2006

The coenzyme A-acylating 2-oxoacid:ferredoxin oxidoreductase and ferredoxin (an effective electron acceptor) were purified from the hyperthermophilic archaeon, Sulfolobus solfataricus P1 (DSM1616). The purified ferredoxin is a monomeric protein with an apparent molecular mass of approximately 11 kDa by SDS-PAGE and of $11,180{\pm}50$ Da by MALDI-TOF mass spectrometry. Ferredoxin was identified to be a dicluster, [3Fe-4S][4Fe-4S], type ferredoxin by spectrophotometric and EPR studies, and appeared to be zinc-containing based on the shared homology of its N-terminal sequence with those of known zinc-containing ferredoxins. On the other hand, the purified 2-oxoacid: ferredoxin oxidoreductase was found to be a heterodimeric enzyme consisting of 69 kDa $\alpha$ and 34 kDa $\beta$ subunits by SDS-PAGE and MALDI-TOF mass spectrometry. The purified enzyme showed a specific activity of 52.6 units/mg for the reduction of cytochrome c with 2-oxoglutarate as substrate at $55^{\circ}C$, pH 7.0. Maximum activity was observed at $70^{\circ}C$ and the optimum pH for enzymatic activity was 7.0 -8.0. The enzyme displays broad substrate specificity toward 2-oxoacids, such as pyruvate, 2-oxobutyrate, and 2-oxoglutarate. Among the 2-oxoacids tested (pyruvate, 2-oxobutyrate, and 2-oxoglutarate), 2-oxoglutarate was found to be the best substrate with $K_m$ and $k_{cat}$ values of $163\;{\mu}M$ and $452\;min^{-1}$, respectively. These results provide useful information for structural studies on these two proteins and for studies on the mechanism of electron transfer between the two.

• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.679-679
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• 2003