• Journal of Microbiology and Biotechnology
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• v.26 no.6
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• pp.1046-1056
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• 2016

RV-23 is a melittin-related antibacterial peptide (MRP) with lower cytotoxicity than either melittin or AR-23, another MRP. The aim of this study was to explore the mechanism of RV-23's antibacterial selectivity and its hemocompatibility. The results showed that all the peptides exhibited lytic activity against Staphylococcus aureus and Escherichia coli, with RV-23 showing the highest potency. Moreover, RV-23 had lower cytotoxicity than melittin or AR-23 at their minimal inhibitory concentration. In addition, CD experiments showed that melittin, RV-23, and AR-23 all had a typical α-helical structure, and RV-23 had the lowest α-helix content. The structural information showed that RV-23 has the lowest hydrophobicity and highest hydrophobic moment. Because hydrophobicity and α-helix content are believed to correlate with hemolysis, the results indicate that the selective lytic activity against bacteria of RV-23 may be due to its low hydrophobicity and α-helicity, which lead to low cytotoxicity without affecting antibacterial activity. Furthermore, RV-23 did not affect the structure and function of blood components such as red blood cells, platelets, albumin, and the blood coagulation system. In conclusion, RV-23 is a cell-selective antibacterial peptide with high hemocompatibility due to its unique structure.

• Journal of Environmental Science International
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• v.6 no.2
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• pp.189-194
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• 1997

Toxic peptides from hornet venom, mastoparan and mastoparan-B were synthesized us- ing the solid phase peptide synthesis method and investigated the interaction of them with phospholipid bilayer, antibacterial activity, and hemolytic activity. Both toxic peptides could induce dye release at a low concentration in neutral liposome. The binding affinity of mastoparan-B for neutral liposome was smaller than that for acidic one. Mastoparan and mastoparan-B had strong antibacterial activity for gram-positive bacteria, but weak or potent activity for gram-negative ones, respectively. Mastoparan and mastoparan-B lysed erythrocyte very little up to 5 $\mu$M.

• Journal of Life Science
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• v.27 no.1
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• pp.50-56
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• 2017

An antibacterial peptide was purified from an acidified gill extract of the pufferfish Takifugu pardalis. The acidified gill extract was put through a Sep-Pak C18 solid phase extraction cartridge using a stepwise gradient and divided into a flow-through (F.T.) and 60% methanol fraction (RM 60). Among the eluents, RM 60 had potent antibacterial activity against Bacillus subtilis KCTC 1021. RM 60 was partially purified on a cationic-exchange column (SP-5PW) by a linear gradient, and the antibacterial peptide was then further purified, using a series of cationic-exchange and $C_{18}$ reversed-phase HPLC columns. For characterization of the purified peptide, its molecular weight and amino acid sequence were analyzed by MALDI-TOF MS and Edman degradation. The molecular weight of the peptide was about 1171.6 Da. The amino acid sequence of the peptide was partially determined as: STKEKAPRKQ. A comparison of the N-terminal amino acid sequence of the purified peptide with that of other known polypeptides revealed high homology with the N-terminus of the histone H3 protein, which belongs to the histone H3 family. Thus, this peptide was designated as a puffer fish gill (PFG)-related antimicrobial peptide. This is the report to describe an antimicrobial function for the N-terminus of histone H3 of an animal species. The findings suggest that this peptide plays a significant role in the innate defense system of the pufferfish.

• Bulletin of the Korean Chemical Society
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• v.26 no.1
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• pp.161-164
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• 2005

• Journal of Microbiology and Biotechnology
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• v.22 no.11
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• pp.1588-1590
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• 2012

We compared the mRNA expression profile of the Harmonia axyridis larvae that were either untreated or treated with LPS. The extracted mRNAs were subjected to ACP RT-PCR analysis using a combination of arbitrary primers and oligo (dT) primer. Among the 47 DEGs differentially expressed, we identified a cDNA showing homology with defensin-like antibacterial peptide. The cDNA showed a putative 32-residue signal sequence and a 50-residue mature peptide named harmoniasin. We also investigated the antibacterial activity of the harmoniasin analog, which exhibited potent antibacterial activities against Gramnegative and -positive bacteria strains and it also evidenced no hemolytic activity.

• Journal of Life Science
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• v.31 no.1
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• pp.83-89
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• 2021

Uu-ilys, an i-type lysozyme from spoon worm (Urechis unicinctus), is an innate immune factor that plays an important role in the defense against pathogens. It also possesses non-enzymatic antibacterial activity. Thus, there is a possibility to develop an antimicrobial model peptide from Uu-ilys. In this study, we report the design, production, and antibacterial activity of an Uu-ilys analog that exhibits antibacterial activity. The Uu-ilys structure was fragmented according to its secondary structures to predict the regions with antimicrobial activity using antimicrobial peptide (AMP) prediction tools from different AMP databases. A peptide containing the C-terminal fragment was predicted to exert antimicrobial activity. The chosen fragment was designated as an Uu-ilys analog containing the C-terminal fragment, Uu-ilys-CF. To examine the possibility of developing an AMP using the sequence of Uu-ilys-CF, recombinant fusion protein (TrxA-Uu-ilys-CF) was produced in an expression system that was heterologous. The produced fusion protein was cleaved after methionine leaving Uu-ilys-CF free from the fusion protein. This was then isolated through high performance liquid chromatography and reverse phase column, CapCell-Pak C18. The antibacterial activity of Uu-ilys-CF against different microbial strains (four gram-positive, six gram-negative, and one fungal strain) were assessed through the ultrasensitive radial diffusion assay (URDA). Among the bacterial strains tested, Salmonella enterica was the most susceptible. While the fungal strain tested was not susceptible to Uu-ilys-CF, broad spectrum antibacterial activity was observed.

• Journal of Microbiology and Biotechnology
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• v.29 no.11
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• pp.1707-1716
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• 2019

The development of new antimicrobial agents is essential for the effective treatment of diseases such as sepsis. We previously developed a new short peptide, Pap12-6, using the 12 N-terminal residues of papiliocin, which showed potent and effective antimicrobial activity against multidrug-resistant Gram-negative bacteria. Here, we investigated the antimicrobial mechanism of Pap12-6 and a newly designed peptide, Pap12-7, in which the 12^th Trp residue of Pap12-6 was replaced with Val to develop a potent peptide with high bacterial selectivity and a different antibacterial mechanism. Both peptides showed high antimicrobial activity against Gram-negative bacteria, including multidrug-resistant Gram-negative bacteria. In addition, the two peptides showed similar anti-inflammatory activity against lipopolysaccharide-stimulated RAW 264.7 cells, but Pap12-7 showed very low toxicities against sheep red blood cells and mammalian cells compared to that showed by Pap12-6. A calcein dye leakage assay, membrane depolarization, and confocal microscopy observations revealed that the two peptides with one single amino acid change have different mechanisms of antibacterial action: Pap12-6 directly targets the bacterial cell membrane, whereas Pap12-7 appears to penetrate the bacterial cell membrane and exert its activities in the cell. The therapeutic efficacy of Pap12-7 was further examined in a mouse model of sepsis, which increased the survival rate of septic mice. For the first time, we showed that both peptides showed anti-septic activity by reducing the infiltration of neutrophils and the production of inflammatory factors. Overall, these results indicate Pap12-7 as a novel non-toxic peptide with potent antibacterial and anti-septic activities via penetrating the cell membrane.

• International Journal of Industrial Entomology and Biomaterials
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• v.31 no.2
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• pp.79-84
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• 2015

A new cecropin-like antimicrobial peptide (Px-CLP) gene was isolated from the immunechallenged larvae of the swallowtail butterfly, Papilio xuthus, by employing annealing control primer (ACP)-based GeneFishing PCR. The full-length cDNA of Px-CLP is 310 nucleotides encoding a 70 amino acid precursor that contains a putative 22-residue signal peptide, a 4-residue propeptide, a presumed 37-residue mature peptide, and an uncommon 7-residue acidic pro-region at the C-terminus. The deduced amino acid sequence of Px-CLP showed significant identities with other Lepidopteran cecropin D type peptides. RT-PCR revealed that the Px-CLP transcript was detected at significant level after injection with bacterial lipopolysaccharide (LPS). The peptides with or without C-terminal acidic sequence region were synthesized on-solid phage and submitted to antibacterial activity assay. The synthetic 37-mer peptide (Px-CLPa), which removed C-terminal acidic sequence region, was showed exclusively antibacterial activity against E. coli ML35; meanwhile, a 44-mer peptide (Px-CLPb) with C-terminal acidic peptide region was not active. This result suggests that Px-CLP is produced as a larger precursor containing a C-terminal pro-region that is subsequently removed by C-terminal modification.

• Journal of Microbiology and Biotechnology
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• v.8 no.5
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• pp.461-465
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• 1998

The suspension culture of an anchorage-dependent cell line (Bok-l) from Bombina orientalis was successful in respects of cost and efficiency. The amount of cells obtained from the suspension culture was almost equivalent to that from the anchorage-dependent culture. This result shows the possibility of suspension culture for scale-up. The cells in suspension produced an antibacterial peptide as much as anchorage-dependent cells did. The cell growth ($6.0\times10^6cells/m\ell$) and viability (>80%) at 10 rpm were higher than that at 0 rpm ($1.9\times10^6cells/m\ell$, 65~80%) and 30 rpm ($1.8\times10^6cells/m\ell$ 40~76%). The size of cells became smaller at the agitation rate of 30 rpm. The antibacterial activities of cell extracts from suspension cultured cells were confirmed against gram-negative and gram-positive bacteria by the inhibition zone assay and the liquid growth inhibition assay.

• Bulletin of the Korean Chemical Society
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• v.30 no.8
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• pp.1839-1844
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• 2009

A 20-residue hybrid peptide CA(1-8)-MA(1-12) (CAMA) incorporating residues 1-8 of cecropin A (CA) and residues 1-12 of magainin 2 (MA) has high antimicrobial activity without toxicity. To investigate the effects of the total positive charges of CAMA on the antibacterial activity and toxicity, a hybrid peptide analogue (CAMA-syn) was designed with substitutions of $Ile^{10}\;and\;Ser^{16}$ with Lys. According to CD spectra, structure of CAMA-syn with increase of cationicity was very similar to that of CAMA in DPC micelle. CAMA-syn showed antimicrobial activity similar with CAMA while CAMA-syn has no hemolytic activity and much lower cytotoxicity against RAW 264.7 macrophage cells than CAMA. Also, CAMA and CAMA-syn significantly inhibited NO production by LPSstimulated RAW264.7 macrophage at 10.0∼20.0 $\mu$M. CAMA-syn displayed salt resistance on antimicrobial activity against Escherichia coli at the physiological concentrations of $CaCl_2\;and\;MgCl_2$. The combination studies of peptides and antibiotics showed that CAMA-syn has synergistic effects with synthetic compound and flavonoid against Enterococcus faecalis and VREF. CAMA-syn can be a good candidate for the development of new antibiotics with potent antibacterial and synergistic activity but without cytotoxicity.