• 한국결정학회:학술대회논문집
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• 한국결정학회 2002년도 정기총회 및 추계학술연구발표회
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• pp.4-4
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• 2002

PDZ domains bind to short segments within target proteins in a sequence-specific fashion. GRIP/ABP family proteins contain six to seven PDZ domains and interact via its sixth PDZ domain (class Ⅱ) with the C-termini of various proteins, including liprin-α. In addition the PDZ456 domain mediates the formation of homo- and heteromultimers of GRIP proteins. To better understand the structural basis of peptide recognition by a class Ⅱ PDZ domain and DZ-mediated multimerization, we determined the crystal structures of the GRIPI PDZ6 domain, alone and in complex with a synthetic C-terminal octapeptide of human liprin-α, at resolutions of 1.5 Å and 1.8 Å, respectively. Remarkably, unlike other class Ⅱ PDZ domains, Ile736 at αB5 rather than conserved Leu732 at αB1 makes a direct hydrophobic contact with the side chain of the Tyr at the -2 position of the ligand. Moreover, the peptide-bound structure of PDZ6 shows a slight reorientation of helix αB, indicating that the second hydrophobic pocket undergoes a conformational adaptation to accommodate the bulkiness of the Tyr's side chain, and forms an antiparallel dimer through an interface located at a site distal to the peptide-binding groove. This configuration may enable formation of GRIP multimers and efficient clustering of GRIP-binding proteins.

• Bulletin of the Korean Chemical Society
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• 제32권5호
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• pp.1751-1753
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• 2011

• Journal of Microbiology and Biotechnology
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• 제21권8호
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• pp.802-807
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• 2011

Cationic liposomes have been actively used as gene delivery vehicle because of their minimal toxicity, but their relatively low efficiency of gene delivery is the major disadvantage of these vectors. Recently, cysteine residue incorporation to HIV-1 Tat peptide increased liposomemediated transfection compared with unmodified Tat peptide. Therefore, we designed a novel modified Tat peptide having a homodimeric (Tat-CTHD, Tat-NTHD) and closed structure (cyclic Tat) simply by using the disulfide bond between cysteines to develop a more efficient and safe nonviral gene delivery system. The mixing of Tat-CTHD and Tat-NTHD with DNA before mixing with lipofectamine increased the transfection efficiency compared with unmodified Tat peptide and lipofectamine only in MCF-7 breast cancer cells and rat vascular smooth muscle cells. However, cyclic Tat did not show any improvement in the transfection efficiency. In the gel retardation assay, Tat-CTHD and Tat-NTHD showed more strong binding with DNA than unmodified Tat and cyclic Tat peptide. This enhancement was only shown when Tat-CTHD and Tat-NTHD were mixed with DNA before mixing with lipofectamine. The effects of Tat- CTHD and Tat-NTHD were also valid in the experiment using DOTAP and DMRIE instead of lipofectamine. We could not find any significant cytotoxicity in the working concentration and more usage of these peptides. In conclusion, we have designed a novel transfection-enhancing peptide by easy homodimerization of Tat peptide, and the simple mix of these novel peptides with DNA increased the gene transfer of cationic lipids more efficiently with no additional cytotoxicity.

• Biomolecules & Therapeutics
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• 제2권4호
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• pp.303-309
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• 1994

The analysis of membrane receptors for hormones and neurotransmitters has progressed considerably by pharmacological and biochemical means and more recently through the use of specific antibodies. Two kinds of antibodies could be produced, one is from synthetic peptides and the other from proteins such as purified receptor. Anti-peptide antibodies gave some advantages; epitope is evident and also receptor purification in quantity is not prerequisite. It can be also applied to the study of receptor structure-activity relationship. The purpose of the present study was 1) to produce and characterize a polyclonal antibody against a synthetic $\beta$2-adrenergic receptor peptide(Phe-Gly-Asn-Phe-Trp-Cys-Phe-Trp-Thr-Ser-Ile-Asp-Val-Leu) and 2) to determine the effects of this antibody on the $\beta$-adrenergic receptor ligand interaction. The peptide sequence contains an amino acid residue such as Asp-113 which was identified as one of important component for receptor-ligand interaction in site-directed mutagenesis studies. Production of antibody was performed by immunization of rabbits through popliteal lymph node with the peptide coupled with Keyhole Limpet Hemocyanin (KLH). The titer of antibody against this peptide was 1 : 1000. The anti-peptide antibody was able to detect a 67 kDa protein band in western blot corresponding to the molecular weight of the $\beta$-adrenergic receptor in partially purified receptor fraction derived from guinea pig lung. The antisera inhibited the specific binding of [$^3$H]dihydroalprenolol to $\beta$-adrenergic receptor in a concentration-dependent manner. The results from this study suggest that the peptide sequence selected in the present study is important for the receptor ligand interaction.

• Asian Pacific Journal of Cancer Prevention
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• 제16권7호
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• pp.2807-2811
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• 2015

Scorpion venom peptides recently have attracted attention as alternative chemotherapeutic agents that may overcome the limitations of current drugs, providing specific cytotoxicity for cancer cells with an ability to bypass multidrug-resistance mechanisms, additive effects in combination therapy and safety. In the present study, BmKn-2 scorpion venom peptide and its derivatives were chosen for assessment of anticancer activities. BmKn-2 was identified as the most effective against human oral squamous cells carcinoma cell line (HSC-4) by screening assays with an $IC_{50}$ value of $29{\mu}g/ml$. The BmKn-2 peptide killed HSC-4 cells through induction of apoptosis, as confirmed by phase contrast microscopy and RT-PCR techniques. Typical morphological features of apoptosis including cell shrinkage and rounding characteristics were observed in treated HSC-4 cells. The results were further confirmed by increased expression of pro-apoptotic genes such as caspase-3, -7, and -9 but decrease mRNA level of anti-apoptotic BCL-2 in BmKn-2 treated cells, as determined by RT-PCR assay. In summary, the BmKn-2 scorpion venom peptide demonstrates specific membrane binding, growth inhibition and apoptogenic activity against human oral cancer cells.

• Bulletin of the Korean Chemical Society
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• 제35권3호
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• pp.783-792
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• 2014

The binding interaction between a hemolytic peptide ${\delta}$-lysin and a zwitterionic lipid bilayer POPC was investigated through a series of molecular dynamics (MD) simulations. ${\delta}$-Lysin is a 26-residue, amphipathic, ${\alpha}$-helical peptide toxin secreted by Staphylococcus aureus. Unlike typical antimicrobial peptides, ${\delta}$-lysin has no net charge and it is often found in aggregated forms in solution even at low concentration. Our study showed that only the monomer, not dimer, inserts into the bilayer interior. The monomer is preferentially attracted toward the membrane with its hydrophilic side facing the bilayer surface. However, peptide insertion requires the opposite orientation where the hydrophobic side of peptide points toward the membrane interior. Such orientation allows the charged residues, Lys and Asp, to have stable salt bridges with the lipid head-group while the hydrophobic residues are buried deeper in the hydrophobic lipid interior. Our simulations suggest that breaking these salt bridges is the key step for the monomer to be fully inserted into the center of lipid bilayer and, possibly, to translocate across the membrane.

• Journal of Microbiology and Biotechnology
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• 제25권6호
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• pp.788-794
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• 2015

Cationic liposomes have been actively used as gene delivery vehicles despite their unsatisfactory efficiencies because of their relatively low toxicity. In this study, we designed novel heterodimeric peptides as nonviral gene delivery systems from TAT and NLS peptides using cysteine-to-cysteine disulfide bonds between the two. Mixing these heterodimeric peptides with DNA before mixing with lipofectamine resulted in higher transfection efficiencies in MCF-7 breast cancer cells than mixing unmodified TAT, NLS, and a simple mixture of TAT and NLS with DNA, but did not show an adverse effect on cell viability. In gel retardation assays, the DNA binding affinities of heterodimeric peptides were stronger than NLS but weaker than TAT. However, this enhancement was only observed when heterodimeric peptides were premixed with DNA before being mixed with lipofectamine. The described novel transfection-enhancing peptide system produced by the heterodimerization of TAT and NLS peptides followed by simple mixing with DNA, increased the gene transfer efficiency of cationic lipids without enhancing cytotoxicity.

• 약학회지
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• 제41권5호
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• pp.588-594
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• 1997

N-(tert-Butoxycarbonyl)-O-(dicyanoethylthiophosphono)-L-tyrosine(7), the key intermediate for the synthesis of thiophosphotyrosine-containing peptide derivat ives, was prepared. For the phosphorylation, we used t-Boc-tyrosine and phosphoramidite in the presence of 1H-tetrazol. For the protection of thiophosphate moiety, cyanoethyl protecting group was used. Thiophosphotyrosine-containing peptides could be used as tools for the elucidation of mechanism of signal transduction pathway and also prepared as PTK inhibitors, PTPase inhibitors and cytosolic protein binding blockers. It may be contributed for the development of potential anticancer agents.

• Mass Spectrometry Letters
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• 제9권1호
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• pp.17-23
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• 2018

Studies on the interactions of amyloidogenic proteins with trace metals, such as copper, have indicated that the metal ions perform a critical function in the early oligomerization process. Herein, we investigate the effects of Cu(II) ions on the active sequence regions of amyloidogenic proteins using electrospray ionization mass spectrometry (ESI-MS) and collision induced dissociation tandem MS (CID-MS/MS). We chose three amyloidogenic peptides NNQQNY, LYQLEN, and VQIVYK from yeast prion like protein Sup35, insulin chain A, and tau protein, respectively. [Cu-peptide] complexes for all three peptides were observed in the mass spectra. The mass spectra also show that increasing Cu(II) concentrations decrease the population of existing peptide oligomers. The tandem mass spectrum of NNQQNY shows preferential binding for the N-terminal region. All three peptides are likely to appear to be in a Cu-monomer-monomer (Cu-M-M) structure instead of a monomer-Cu-monomer (M-Cu-M) structure.

• Bulletin of the Korean Chemical Society
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• 제6권5호
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• pp.300-303
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• 1985

To understand the nature of the linkage between chromophore and apoprotein in the photoreceptor of Stentor coeruleus, a conformational analysis has been carried out on the dipeptide amides linked to the chromophore hypericin using an empirical potential function. The conformational energies for the dipeptide amides of Glu (OHyp)-X-NHMe, where X = Leu, Phe, Asp, and Tyr, have been calculated to investigate the influence of peptide residues in stabilizing conformers. It was found that the increase of acidity of hypericin upon photoexcitation may be facilitated by the formation of intramolecular hydrogen bonds between hydroxyl groups of hypericin and carbonyl groups of peptide backbone, and that the stabilities of dipeptide amides do not significantly depend on peptide residues directly linked to chromophore.