• Food Science of Animal Resources
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• v.36 no.6
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• pp.791-798
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• 2016

Free radicals may attack cells or tissue, leading to chronic diseases, and antioxidant consumption is potentially useful for removing free radicals. Egg proteins may be used as potential sources of antioxidant considering their ability of scavenging free radicals to apply for food or cosmetics industry. In this study, we obtained a natural antioxidant protein from fertilized eggs, which was a dietary supplement in some Asian countries. Meanwhile, antioxidant activities of these proteins were evaluated using different oxidation systems. With increasing incubation time, the antioxidant activity of these proteins increased during 15 d of incubation. The samples on day 15 were performed for isolation of antioxidant protein. The protein, named P4-1 (MW, 45 kDa), was isolated and purified by consecutive chromatographic methods. P4-1 contained 17 amino acids, which was determined by liquid chromatography-mass spectrometry and Amino Acid Analyzer. Moreover, the amino acid sequence was highly similar to that of ovalbumin. Differential scanning calorimetry showed that the denaturation temperature of P4-1 was $57.16^{\circ}C$. Furthermore, P4-1 suggested high oxygen radical-absorbance activity in ${\cdot}OH$ assays, and its antioxidant activity was stable at $30-50^{\circ}C$ in acidic and neutral pH. Thus, these results revealed that P4-1 may be a potential resource as a natural antioxidant.

• BMB Reports
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• v.37 no.2
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• pp.254-259
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• 2004

The wild-type and temperature-sensitive (ts) repressor genes were cloned from the temperate mycobacteriophage L1 and its mutant L1cIts391, respectively. A sequencing analysis revealed that the $131^{st}$ proline residue of the wild-type repressor was changed to leucine in the ts mutant repressor. The 100% identity that was discovered between the two DNA regions of phages L1 and L5, carrying the same sets of genes including their repressor genes, strengthened the speculation that L1 is a minor variant of phage L5 or vice versa. A comparative analysis of the repressor proteins of different mycobacteriophages suggests that the mycobacteriophage-specific repressor proteins constitute a new family of repressors, which were possibly evolved from a common ancestor. Alignment of the mycobacteriophage-specific repressor proteins showed at least 7 blocks (designated I-VII) that carried 3-8 identical amino acid residues. The amino acid residues of blocks V, VI, and some residues downstream to block VI are crucial for the function of the L1 (or L5) repressor. Blocks I and II possibly form the turn and helix 2 regions of the HTH motif of the repressor. Block IV in the L1 repressor is part of the most charged region encompassing amino acid residues 72-92, which flanks the putative N-terminal basic (residues 1-71) and C-terminal acidic (residues 93-183) domains of L1 repressor.

• Toxicological Research
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• v.14 no.4
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• pp.525-533
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• 1998

The covalent interactions of toluenediisocyanate (TDI) with macromolecules were investigated both in vitro and in vivo. In vitro incubations of 2,4- and 2,6-TDI with DNA or proteins resulted in dose-dependent formation of TDI-protein and TDI-DNA adducts. TDI-treated DNA was highly resistant to enzymatic digestion and thermal hydrolysis, but was readily hydrolyzed under acidic conditions by releasing its corresponding toluenediamine (TDA), suggesting that TDI caused the crosslinking of DNA. Reaction of TDI with albumin and globin resulted in the formation of several adducts, and some adducts were formed in blood of TDI-treated rats in a dose-dependent fashion. Administration of TDI to rats resulted also in a dose-dependent binding of TDI to hepatic tissue. Levels of TDI-albumin adducts were 10 times higher than those of TDI-globin adducts; the biological half lives of TDI-albumin and TDI-globin adducts were 1.2 and 12.5 days, respectively. Globin adducts were detected up to 28 days after the treatment. Hepatic TDI protein adducts were persistent for a substantial period whereas the levels of hepatic TDI-DNA adduct were decreased rapidly. These results indicate that the isocyanato group of TDI is not readily hydrolyzed under physiological conditions, is transported to other organs, and is bound to DNA and/or proteins without further metabolic activation. As the adducted products degrade in the body, TDA is released and introduced to the liver. TDA may additionally bind to hepatic tissue after metabolic activation. Thus, the toxic effect of TDI exposure is considered to persist during the lifetime of the adducted biological macromolecules.

• Proceedings of the Korean Society of Life Science Conference
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• 2002.12a
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• pp.20-47
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• 2002

Two-dimensional gel electrophoresis (2-DE) maps for human stomach tissue proteins have been prepared by displaying the protein components of the tissue by 2-DE and identifying them using mass spectrometry. This will enable us to present an overview of the proteins expressed In human stomach tissues and lays the basis for subsequent comparative proteome analysis studies with gastric diseases such as gastric cancer. In this study, 2-DE maps of soluble fraction proteins were prepared on two gel images with partially overlapping pH ranges of 4-7 and 6-9. On the gels covering pH 4-7 and pH 6-9, about 900 and 600 protein spots were detected on silver staining, respectively. For protein identification, proteins spots on micropreparative gels stained by colloidal Coomassie Brilliant Blue G-250 were excised, digested in-gel with trypsln, and analyzed by peptide mass fingerprinting with delayed extraction-matrix assisted laser dosorption/ionization-mass spectrometry (DE-MALDI-MS). In all, 243 protein spots (168 spots in acidic map and 75 spots in basic map) corresponding to 136 different proteins were identified. Besides these principal maps, maps of lower resolution, i.e. overview maps (displayed on pH 3-10 gels) for total homogenate and soluble fraction, are also presented with some identifications mapped on them. Based on the 2-DE maps presented in this study, a 2-DE database for human stomach tissue proteome has been constructed and available at http://proteome.gsnu.ac.kr/DB/2DPAGE/Stomach/. The 2-DE maps and the database resulting from this study will serve important resources for subsequent proteomic studies for analyzing the normal protein variability in healthy tissues and specific protein variations in diseased tissues.

• Molecules and Cells
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• v.37 no.3
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• pp.264-269
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• 2014

The molecular interaction between tumor suppressor p53 and the anti-apoptotic Bcl-2 family proteins plays an essential role in the transcription-independent apoptotic pathway of p53. In this study, we investigated the binding of p53 DNA-binding domain (p53DBD) with the anti-apoptotic Bcl-2 family proteins, Bcl-w, Mcl-1, and Bcl-2, using GST pull-down assay and NMR spectroscopy. The GST pull-down assays and NMR experiments demonstrated the direct binding of the p53DBD with Bcl-w, Mcl-1, and Bcl-2. Further, NMR chemical shift perturbation data showed that Bcl-w and Mcl-1 bind to the positively charged DNA-binding surface of p53DBD. Noticeably, the refined structural models of the complexes between p53DBD and Bcl-w, Mcl-1, and Bcl-2 showed that the binding mode of p53DBD is highly conserved among the anti-apoptotic Bcl-2 family proteins. Furthermore, the chemical shift perturbations on Bcl-w, Mcl-1, and Bcl-2 induced by p53DBD binding occurred not only at the p53DBD-binding acidic region but also at the BH3 peptide-binding pocket, which suggests an allosteric conformational change similar to that observed in Bcl-$X_L$. Taken altogether, our results revealed a structural basis for a conserved binding mechanism between p53DBD and the anti-apoptotic Bcl-2 family proteins, which shed light on to the molecular understanding of the transcription-independent apoptosis pathway of p53.

• Journal of Life Science
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• v.27 no.7
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• pp.826-833
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• 2017

The rising concentration of atmospheric carbon dioxide is causing ocean acidification and global warming. The seahorse is an important species in marine ecosystems and fishery markets, however, their populations have recently decreased due to ocean acidification. As a result, we examined changes in the physiological responses of the spotted seahorse Hippocampus kuda when it was exposed to acidic sea water (pH 6.0, 6.5, and 7.0) and normal seawater (pH 8.0 as the control) over a period of 15 days. As the pH decreased, the seahorses' body weight and length also decreased. Components in body of ash, the crude lipids and crude proteins also differed significantly with changes in pH, due to stress caused by the seahorses' exposure to the acidic water conditions. The superoxide dismutase levels were significantly lower in the pH 6.0 and 6.5 groups than they were in the pH 7.0 and pH 8.0 groups. However, the catalase and glutathione levels were significantly higher in the acidic sea water groups. We suggest that decreasing the pH level of rearing water induces a stress response in H. kuda, damaging their ability to maintain their homeostasis and energy metabolism. Antioxidant enzymes are generally sensitive to acidic stress; in this study, the antioxidant activity was significantly affected by the pH level of the rearing water. These results indicate that physiological stress, induced by exposure to acidification, induces an antioxidant reaction, which can reduce general components in the body and the growth of H. kuda.

• BMB Reports
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• v.33 no.4
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• pp.300-307
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• 2000

Two glycoproteins were purified and biochemically characterized from the lichen X. parietina. Both behaved as enzymes with arginase activity and haemaglutinins. Secreted arginase (SA) contained galactose and glucose in the saccharide moiety and an isoelectric point of 4.54. The algal binding-protein (ABP) had N-acetyl-glucosamine and glucose as glycosidic residues and an isoelectric point of 3.53. Both proteins had the same molecular mass (58.6 kDa) and the same qualitative amino acidic composition. The results allowed us to consider these glycoproteins as isolectins, which have significant physiological roles in the relationship between photobiont and mycobiont of symbiotic association.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.36 no.1
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• pp.24-29
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• 2004

Alkaline cellulolytic enzymes from cultured medium of Coprinus cinereus 2249 were purified with gel and ion-exchange chromatography and characteristics of those enzyme proteins were investigated. A fiber length distribution and a crystallinity of cellulose and sugar composition of enzyme treated Mixed Office Wastepaper(MOW) and Unbleached Kraft Pulp(UKP) were analysed. The conclusion could summarized as follows; \circled1 Alkaline and acidic, endo- and exo-glucanases were purified from cultured medium of Coprinus cinereus 2249. \circled2 The approximate molecular weight of alkaline endo-glucanase was 42 kDa, and also that of alkaline exo-glucanase was 50 kDa. A fiber length distribution and a crystallization of cellulose and sugar composition of enzyme treated MOW and UKP were not so much changed with original paper and pulp.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.529-529
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• 2012

Dispersion of carbon nanotubes in biocompatible media are of particular interest for diverse biomedical and nanomedicine applications. Various biomolecules and biopolymers such as DNA, proteins, poly L-lysine, starch, gelatin, steroid biosurfactants, and chitosan have shown capability for the effective dispersion of carbon nanotubes in water. Chitosan has demonstrated capacity for effective dispersion of single-walled carbon nanotubes (SWCNTs) in acidic medium and it also showed tendency to preferentially disperse smaller diameter nanotubes. Chemical functionalizations of chitosan enable its solubility in neutral pH water by reducing the intra and inter molecular hydrogen bonding. Herein, we present a neutral pH water soluble chitosan derivative, chitosan-hydroxyphenyl acetamide (CHPA), obtained by functionalizing the amino groups of chitosan with 4-hydroxyphenyl acetic acid, as an efficient biocompatible dispersant for debundling and solubilization of SWNTs in neutral aqueous solutions. Various process conditions for individual dispersion of SWCNTs are analyzed based on optical absorption and Raman spectroscopy.

• Macromolecular Research
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• v.15 no.7
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• pp.671-675
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• 2007

Soybean proteins appear to harbor a great deal of potential as functional ingredients due to the fact that they are composed of highly bioavailable peptides and amino acids. To develop drink- or gel-type foods formulated with soybean protein, the physicochemical properties of intact and chemically modified soy glycinin were assessed. Maleylation to soy glycinin altered the surface charges of glycinin via the modification of lysine residues, and subsequently generated the dissociation of glycinin subunits owing to the increase in charge repulsion. This modification thus improved the solubility of glycinin, particularly under acidic pH conditions. It is worthy of note that maleylation increased the susceptibility of the basic subunits of mTGase and the formation of a substantial quantity of molecules at a low protein solution concentration. The results of dynamic rheological studies indicated that the 5% intact glycinin progressively formed the gel with mTGase treatment in a concentration-dependent manner, but maleylated-glycinin did not.