• Journal of Veterinary Clinics
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• v.21 no.3
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• pp.253-258
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• 2004

DNA double-strand break (DSB) is a serious treat for the cells including mutations, chromosome rearrangements, and even cell death if not repaired or misrepaired. Ku heterodimer regulatory DNA binding subunits (Ku70/Ku80) bound to double strand DNA breaks are able to interact with 470-kDa DNA-dependent protein kinase catalytic subunit (DNA-PKcs), and the interaction is essential for DNA-dependent protein kinase (DNA-PK) activity. The Ku80 mutants were designed to bind Ku70 but not DNA end binding activity and the peptides were treated in breast cancer cells for co-therapy strategy to see whether the targeted inhibition of DNA-dependent protein kinase (DNA-PK) activity sensitized breast cancer cells to ionizing irradiation or chemotherapy drug to develop a treatment of breast tumors by targeting proteins involved in damage-signaling pathway and/or DNA repair. We designed domains of Ku80 mutants, 26 residues of amino acids (HN-26) as a control peptide or 38 (HNI-38) residues of amino acids which contain domains of the membrane-translocation hydrophobic signal sequence and the nuclear localization sequence, but HNI-38 has additional twelve residues of peptide inhibitor region. We observed that the synthesized peptide (HNI-38) prevented DNA-PKcs from binding to Ku70/Ku80, resulting in inactivation of DNA-PK complex activity in breast cancer cells (MDA-465 and MDA-468). Consequently, the peptide treated cells exhibited poor to no DNA repair, and became highly sensitive to irradiation or chemotherapy drugs. The growth of breast cancer cells was also inhibited. These results demonstrate the possibility of synthetic peptide to apply breast cancer therapy to induce apoptosis of cancer cells.

• BMB Reports
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• v.42 no.6
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• pp.380-386
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• 2009

In neurodegenerative diseases, such as Alzheimer' and Parkinson', microglial cell activation is thought to contribute to CNS injury by producing neurotoxic compounds. Prothrombin and kringle-2 increase levels of NO and the mRNA expression of iNOS, IL-1$\beta$, and TNF-$\alpha$ in microglial cells. In contrast, the human prothrombin kringle-2 derived peptide NSA9 inhibits NO release and the production of pro-inflammatory cytokines such as IL-1$\beta$, TNF-$\alpha$, and IL-6 in LPS-activated EOC2 microglia. In this study, we investigated the anti-inflammatory effects of NSA9 in human prothrombin- and kringle-2-stimulated EOC2 microglia. Treatment with 20-100 ${\mu}M$ of NSA9 attenuated both prothrombin- and kringle-2-induced microglial activation. NO production induced by MAPKs and NF-$\kappa$B was similarly reduced by inhibitors of ERK (PD98059), p38 (SB203580), NF-$\kappa$B (N-acetylcysteine), and NSA9. These results suggest that NSA9 acts independently as an inhibitor of microglial activation and that its effects in EOC2 microglia are not influenced by the presence of kringle-2.

• Journal of Microbiology and Biotechnology
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• v.18 no.2
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• pp.328-333
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• 2008

A series of pep tides binding to the HCV NS5B polymerase was selected from phage display peptide libraries. A conserved motif of Ser-Arg-X-Arg/Leu was identified among the selected peptides, and Pep2 (Trp-Ser-Arg-Pro-Arg-Ser-Leu) was chosen for further characterization. The binding of Pep2 to HCV NS5B in vivo was shown by a yeast two-hybrid assay and by subcellular colocalization analysis using immunofluorescence confocal microscopy. The in vitro interaction was also confirmed by GST pulldown assay. The replication of the HCV 1b subgenomic replicon was efficiently inhibited by the presence of the peptide. By using a subtractive biopanning against Pep2, the binding site of the peptide was mapped at the pocket of Pro388 to Pro391 in the thumb subdomain of the polymerase. A yeast two-hybrid analysis using Pro388Ala and Pro391Ala mutants of NS5B confirmed the binding.

• Journal of Marine Bioscience and Biotechnology
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• v.10 no.1
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• pp.1-8
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• 2018

The objective of this study was to purify and characterize the ${\beta}-secretase$ inhibitor from enzymatic hydrolysates of blackfin flounder muscle, for development of a novel anti-dementia agent that may be used in the drug or functional food industries. ${\beta}-secretase$ inhibitory peptide was purified from various enzymatic hydrolysates of blackfin flounder muscle. Among six enzymatic hydrolysates, the Alcalase hydrolysate revealed highest ${\beta}-secretase$ inhibitory activity. Consecutive purification of the blackfin flounder muscle hydrolysate using Sephadex G-25 column chromatography and octadecylsilane C18 reversed phase HPLC techniques were used to isolate a potent ${\beta}-secretase$ inhibitory peptide composed of 5 amino acids, Leu-Thr-Gln-Asp-Trp (MW: 526.7 Da). The $IC_{50}$ value of purified ${\beta}-secretase$ inhibitory peptide was $126.93{\mu}M$. Results of this study suggest that peptides derived from blackfin flounder muscle may be beneficial as anti-dementia compounds in functional foods or as pharmaceuticals.

• Animal cells and systems
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• v.12 no.4
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• pp.211-217
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• 2008

Bax, a pro-apoptotic member of Bcl-2 family proteins, plays a central role in the mitochondria-dependent apoptosis. Apoptotic signals induce the translocation of Bax from cytosol into the mitochondria, which triggers the release of apoptogenic molecules such as cytochrome C and apoptosis-inducing factor, AIF. Bax-inhibiting peptide(BIP) is a cell permeable peptide comprised of five amino acids designed from the Bax-interaction domain of Ku70. Because BIP inhibits Bax translocation and Bax-mediated release of cytochrome C, BIP suppresses Bax-dependent apoptosis. In this study, we observed that BIP inhibited staurosporine-induced neuronal death in cultured cerebral cortex and cerebellar granule cells, but BIP failed to rescue granule cells from trophic signal deprivation-induced neuronal death, although both staurosporine-induced and trophic signal deprivation-induced neuronal death are dependent on Bax. These findings suggest that the mechanisms of the Bax activation may differ depending on the type of cell death induction, and thus BIP exhibits selective suppression of a subtype of Bax-dependent neuronal death.

• Preventive Nutrition and Food Science
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• v.3 no.4
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• pp.379-381
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• 1998

An angiotensin converting enzyme (ACE) inhibitor was isolated and partially purified from bovine blood plasma. Bovine blood plasma was obtained after removing blood cells by centrifugation, followed by the addition of anticoagulant to whole bovine blood. To precipitate plasma proteins, bovine blood plasma was treated with 4% trichloroacetic acid (TCA) as a final concentration .An ACE inhibitor was isolated from TCA supernatnat, using ultrafiltration, gel permeation chormatography, and reverse-phase high pressure liquid chromatogrpahy. The ACE inhibitor purified from TCA supernatant had IC50 values of 9.4$\mu$M.

• Bulletin of the Korean Chemical Society
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• v.20 no.3
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• pp.301-306
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• 1999

Hepatitis C virus (HCV) has been known to be an enveloped virus with a positive strand RNA genome and the major agent of the vast majority of transfusion associated cases of hepatitis. For viral replication, HCV structural proteins are first processed by host cell signal peptidases and NS2/NS3 site of the nonstructural protein is cleaved by a zinc-dependent protease NS2 with N-terminal NS3. The four remaining junctions are cleaved by a separate NS3 protease. The solution conformations of NS4B/5A, NS5A/5B substrates and NS5A/5B inhibitor have been determined by two-dimensional nuclear magnetic resonance (NMR) spectroscopy. NMR data suggested that the both NS5A/5B substrate and inhibitor appeared to have a folded tum-like conformation not only between P1 and P6 position but also C-terminal region, whereas the NS4B/5A substrate exhibited mostly extended conformation. In addition, we have found that the conformation of the NS5A/5B inhibitor slightly differs from that of NS5A/5B substrate peptide, suggesting different binding mode for NS3 protease. These findings will be of importance for designing efficient inhibitor to suppress HCV processing.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.10
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• pp.4353-4358
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• 2014

Background: PI3/AKT and NF-kB signaling pathways are constitutively active in acute myeloid leukemia and cross-talk between the two has been shown in various cancers. However, their role in acute myeloid leukemia has not been completely explored. We therefore used cell penetrating inhibitor peptides to define the contributions of AKT and NF-kB to survival and multi drug resistance (MDR) in HL-60 cells. Materials and Methods: Inhibition of AKT and NF-kB activity by AKT inhibitor peptide and NBD inhibitor peptide, respectively, resulted in decreased expression of mRNA for the MDR1 gene as assessed by real time PCR. In addition, treatment of HL-60 cells with AKT and NBD inhibitor peptides led to inhibition of cell viability and induction of apoptosis in a dose dependent manner as detected by flow cytometer. Results: Finally, co-treatment of HL-60 cells with sub-optimal doses of AKT and NBD inhibitor peptides led to synergistic apoptotic responses in AML cells. Conclusions: These data support a strong biological link between NF-kB and PI3-kinase/AKT pathways in the modulation of antiapoptotic and multi drug resistant effects in AML cells. Synergistic targeting of these pathways using NF-kB and PI3-kinase/AK inhibitor peptides may have a therapeutic potential for AML and possibly other malignancies with constitutive activation of these pathways.

• Journal of Plant Biotechnology
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• v.38 no.1
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• pp.87-93
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• 2011

S-Adenosylmethionine decarboxylase (SAMDC; EC 4.1.4.50), a key enzyme for polyamines biosynthesis, was tightly regulated for homeostatic levels. Carnation SAMDC gene (CSDC9) has an small upstream open reading frame (uORF) of 54 amino acids in 5'-leader sequence. To explore the functional mechanism of uORFs in controlling translation, we used a GUS reporter gene driven with the 35S promoter and uORF region of SAMDC gene for making transgenic tobacco plants. In our experiment, there were a translational inhibition of its downstream GUS ORF by SAMDC uORF sequence or SAMDC uORF protein. Expecially, translational inhibition was most effective in point-mutated construct, in which the start codon was changed. Therefore, this results suggested the ribosomal stalling might be involved in this translational inhibitory process. The frame shift in amino acid sequence of SAMDC uORF with start codon and stop codon resulted in a moderate increasing in GUS activity, suggesting the native amino acid sequence was important for a function as a translational inhibitor. Also, we showed that the production of GUS protein was significantly inhibited in the presence of the small uORF using histochemical analysis of GUS expression in seedlings and tobacco flowers. Importantly, the small uORF sequence induced a real peptide of 5.7 kDa, which was provided the presence of SAMDC uORF peptide band using an in vitro transcription/translation system. The peptide product of uORF might interact with other components of translational machinery as well as polyamines, which was resulted from that polyamine treatment was inhibited GUS protein band in SDS-PAGE experiment.

• Korean Journal of Food Science and Technology
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• v.31 no.3
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• pp.848-854
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• 1999

Inhibitory compounds of angiotensin converting enzyme (ACE) were separated from Doenjang (traditional Korean fermented soybean paste). Water extracts from Doenjang which showed ACE inhibitory activity were separated with gel permeation chromatography (GPC), in which two fractions with high ACE inhibitory activities were obtained. The first fraction from GPC was further isolated by semi-preparative reverse phase preparative-HPLC (high performance liquid chromatography) and 2-dimensional electrophoresis/thin layer chromatography (TLC). The purified spot had molecular weight of 759 daltons and ninhydrin-positive non-peptide. The second fraction from GPC was also further isolated by semi-preparative reverse phase HPLC and $NH_2-column$ HPLC. One fraction with high ACE inhibitory activity was purified and characterized. Molecular weight of this fraction by LC-MS was 272.34 daltons. The active fraction was identified as Arg-Pro with ACE $IC_{50}$ of $92\;{\mu}M$.