• BMB Reports
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• v.39 no.3
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• pp.319-328
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• 2006

SecA protein, a cytoplasmic ATPase, plays a central role in the secretion of signal peptide-containing proteins. Here, we examined effects of signal peptide and ATP on the oligomerization, conformational change, and membrane binding of SecA. The wild-type (WT) signal peptide from the ribose-binding protein inhibited ATP binding to soluble SecA and stimulated release of ATP already bound to the protein. The signal peptide enhanced the oligomerization of soluble SecA, while ATP induced dissociation of SecA oligomer. Analysis of SecA unfolding with urea or heat revealed that the WT signal peptide induces an open conformation of soluble SecA, while ATP increased the compactness of SecA. We further obtained evidences that the signal peptide-induced oligomerization and the formation of open structure enhance the membrane binding of SecA, whereas ATP inhibits the interaction of soluble SecA with membranes. On the other hand, the complex of membrane-bound SecA and signal peptide was shown to resume nucleotide-binding activity. From these results, we propose that the translocation components affect the degree of oligomerization of soluble SecA, thereby modulating the membrane binding of SecA in early translocation pathway. A possible sequential interaction of SecA with signal peptide, ATP, and cytoplasmic membrane is discussed.

• Preventive Nutrition and Food Science
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• v.15 no.4
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• pp.282-286
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• 2010

To isolate a calcium-binding peptide from chlorella protein hydrolysates, chlorella protein was extracted and hydrolyzed using Flavourzyme, a commercial protease. The degree of hydrolysis and calcium-binding capacity were determined using trinitrobenzenesulfonic acid and orthophenanthroline methods, respectively. The enzymatic hydrolysis of chlorella protein for 6 hr was sufficient for the preparation of chlorella protein hydrolysates. The hydrolysates of chlorella protein were then ultra-filtered under 5 kDa as molecular weight. The membrane-filtered solution was fractionated using ion exchange, reverse phase, normal phase chromatography, and fast protein liquid chromatography to identify a calcium-binding peptide. The purified calcium-binding peptide had a calcium binding activity of 0.166 mM and was determined to be 700.48 Da as molecular weight, and partially identified as a peptide containing Asn-Ser-Gly-Cys based on liquid chromatography/electrospray ionization tandem mass spectrum.

• Microbiology and Biotechnology Letters
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• v.33 no.4
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• pp.319-321
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• 2005

We have previously reported the isolation and characterization of peptides binding to $TiO_{2}$ nanoparticles from phage display peptide libraries. One of the peptides (PEP9) was selected and mutant peptide-displaying phages were produced by alanine scanning mutagenesis. The mutant phages were subjected to binding analysis to $TiO_{2}$ nanoparticles. When the proline at residue 4 was substituted by alanine, the binding activity was reduced to $10\%$ of that of wild type PEP9. Substitution of valine at residue 2, serine at residue 3, and isoleucine at residue 5 also decreased the binding to $40\%$. Based on these observations, we concluded that the three dimensional structure generated by residues 2-5 was the critical factor for the binding between PEP9 and the nanoparticle.

• Microbiology and Biotechnology Letters
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• v.51 no.3
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• pp.243-249
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• 2023

We recently found that the insect-derived antimicrobial peptide CopA3 (LLCIALRKK) directly binds to and inhibits the proteolytic activation of caspases, which play essential roles in apoptotic processes. However, the mechanism of CopA3 binding to caspases remained unknown. Here, using recombinant GST-caspase-3 and -6 proteins, we investigated the mechanism by which CopA3 binds to caspases. We showed that replacement of cysteine in CopA3 with alanine caused a marked loss in its binding activity towards caspase-3 and -6. Exposure to DTT, a reducing agent, also diminished their interaction, suggesting that this cysteine plays an essential role in caspase binding. Experiments using deletion mutants of CopA3 showed that the last N-terminal leucine residue of CopA3 peptide is required for binding of CopA3 to caspases, and that C-terminal lysine and arginine residues also contribute to their interaction. These conclusions are supported by binding experiments employing direct addition of CopA3 deletion mutants to human colonocyte (HT29) extracts containing endogenous caspase-3 and -6 proteins. In summary, binding of CopA3 to caspases is dependent on a cysteine in the intermediate region of the CopA3 peptide and a leucine in the N-terminal region, but that both an arginine and two adjacent lysines in the C-terminal region of CopA3 also contribute. Collectively, these results provide insight into the interaction mechanism and the high selectivity of CopA3 for caspases.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.7
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• pp.1206-1211
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• 2004

This study was conducted to evaluate the effects of selenium binding yeast peptide supplementation on growth performance, tissue Se, serum glutathione peroxidase activity and meat quality in finishing pigs. A total of eighty (Duroc${\times}$Yorkshir${\times}$Landrace) pigs (82.88$\pm$1.23 kg average initial body weight) were used in a 35-day assay. Dietary treatments included 1) CON (basal diet), 2) SY1 (CON diet＋0.05％ selenium binding yeast peptide), 3) SY2 (CON diet＋0.l％ selenium binding yeast peptide) and 4) SY3 (CON diet＋0.2％ selenium binding yeast peptide). Overall period, average daily gain of pigs fed selenium binding yeast peptide diet was higher than that of pigs fed CON diet, however, there was not significant difference (p＞0.05). L＊ (lightness) value of M. longissimus dorsi was higher in SY2 than CON and SY3 (p＜0.05). a＊ (redness) value of M. longissimus dorsi was lower in CON than other treatments (p＜0.05). Selenium content in serum was increased as adding selenium binding yeast peptide compared to pigs fed CON diet. However, there was not significantly different among the treatments (p＞0.05). Selenium content of M. longissimus dorsi was higher in SY2 (0.021 $\mu$g/g) and SY3 (0.031 $\mu$g/g) than CON diet (0.008 $\mu$g/g) (p＜0.05). Selenium content of kidney was increased in SY2 I and SY3 compared to pigs fed CON and SY1 (p＜0.05). Selenium content of liver was higher in SY1 than CON (p＜0.05). In conclusion, it is suggested that selenium content could be accumulated in M. longissimus dorsi, kidney and liver by selenium binding yeast peptide supplementation, and meat color of M. longissimus dorsi could be affected by selenium binding yeast peptide supplementation.

• Journal of Applied Biological Chemistry
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• v.53 no.3
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• pp.174-178
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• 2010

Calcium and iron binding peptides were prepared by enzymatic hydrolysis and ultrafiltration of rice bran protein (RBP), which was isolated from defatted rice bran by phytase and xylanase treatment and ultrasonication. The isolated RBP had a molecular weight in the range of 10-66 kDa. The extracted proteins were hydrolyzed using Flavourzyme for 6 hr. After ultrafiltration under 5 kDa as molecular weight, the peptides were fractionated into 4 peaks by Sephadex G-15 gel permeation chromatography, and each fraction was determined for calcium and iron binding activity. As the result, Fl and F2 fractions were the best candidate for calcium and iron chelation, respectively. These results suggest that the calcium and iron binding peptides can be used as functional food additives in food industry.

• Mass Spectrometry Letters
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• v.6 no.3
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• pp.80-84
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• 2015

Here, we demonstrate the use of MALDI-TOF as a fast and simple analytical approach to evaluate the DNA-binding capability of various peptides. Specifically, by varying the amino acid sequence of the peptides consisting of lysine (K) and tryptophan (W), we identified peptides with strong DNA-binding capabilities using MALDI-TOF. Mass spectrometric analysis reveals an interesting novel finding that lysine residues show sequence selective preference, which used to be considered as mediator of electrostatic interactions with DNA phosphate backbones. Moreover, tryptophan residues show higher affinity to DNA than lysine residues. Since there are numerous possible combinations to make peptide oligomers, it is valuable to introduce a simple and reliable analytical approach in order to quickly identify DNA-binding peptides.

• Bulletin of the Korean Chemical Society
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• v.31 no.1
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• pp.202-204
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• 2010

• Proceedings of the Microbiological Society of Korea Conference
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• 2005.05a
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• pp.132-134
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• 2005

The CC chemokine, monocyte chemoattractant protein-1 (MCP-1), plays a crucial role in the initiation of atherosclerosis and has direct effects that promote angiogenesis. To develop a specific inhibitor for MCP-1-induced angiogenesis, we performed in vitro selection employing phage display random peptide libraries. Most of the selected peptides were found to be homologous to the second extracellular loops of CCR2 and CCR3. We synthesized the peptide encoding the homologous sequences of the receptors and tested its effect on the MCP-1 induced angiogenesis. Surface Plasmon Resonance measurements demonstrated specific binding of the peptide to MCP-1 but not to the other homologous protein, MCP-3. Flow cytometry revealed that the peptide inhibited the MCP-1 binding to THP-1 monocytes. Moreover, CAM and rat aortic ring assays showed that the peptide inhibited MCP-1 induced angiogenesis. Our observations indicate that the MCP-1-binding peptide exerts its anti-angiogenic effect by interfering with the interaction between MCP-1 and its receptor.

• Bulletin of the Korean Chemical Society
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• v.23 no.10
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• pp.1483-1486
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• 2002