• Journal of Microbiology and Biotechnology
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• v.8 no.6
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• pp.595-600
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• 1998

In order to investigate a relationship of the structure-antifungal and hemolytic activities between cecropin A(1-8)-magainin 2(1-12) and cecropin A(1-8)-melittin(1-12) hybrid peptides, several analogues with amino acid substitution at positions 10 (Ile) and 16 (Ser) were designed and synthesized. The increase of the hydrophobicity by substituting with Leu, Phe, and Trp at position 16 in cecropin A(1-8)-magainin 2(1-12) did not have a significant effect on antifungal activity but caused a remarkable increase in hemolytic activity. These results indicate that the hydrophobic property at position 16 of cecropin A(1-8)-magainin 2(1-12) is more correlated to hemolytic activity than to antifungal activity. Replacement with Pro at position 10 of cecropin A(1-8)- magainin 2(1-12) and cecropin A(1-8)-melittin (1-12) caused a remarkable decrease in a-helical contents in the 50% TFE solution and induced a reduction in lytic activity against Aspergillus flavus, and Aspergillus fumigatus. These results demonstrate that flexibility at the central hinge region is essential for lytic activity against fungal cells and $\alpha$-helicity of the peptides.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.13
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• pp.5433-5436
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• 2014

Conventional chemotherapy against hepatocellular carcinoma typically causes various side effects. Our previous study showed that cecropin of Musca domestica can induce apoptosis in human hepatocellular carcinoma BEL-7402 cells in vitro. However, whether cecropin inhibits BEL-7402 cell in vivo and the question of possible side effects remained undentified. The present study confirmed tumor-inhibitory effects of cecropin in vivo, and furthermore strongly suggested that cecropin cytotoxicity in BEL-7402 cells in vivo may be mainly derived from its pro-apoptotic action. Specifically, we found that cecropin exerted no obvious side effects in tumor-bearing mice as it had no significant hematoxicity as well as visceral toxicity. Therefore, cecropin may be a potential candidate for further investigation as an antitumor agent against hepatocellular carcinoma.

• BMB Reports
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• v.46 no.5
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• pp.282-287
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• 2013

Cecropin A and papiliocin are novel 37-residue cecropin-like antimicrobial peptides isolated from insect. We have confirmed that papiliocin possess high bacterial cell selectivity and has an ${\alpha}$-helical structure from $Lys^3$ to $Lys^{21}$ and from $Ala^{25}$ to $Val^{35}$, linked by a hinge region. In this study, we demonstrated that both peptides showed high antimicrobial activities against multi-drug resistant Gram negative bacteria as well as fungi. Interactions between these cecropin-like peptides and phospholipid membrane were studied using CD, dye leakage experiments, and NMR experiments, showing that both peptides have strong permeabilizing activities against bacterial cell membranes and fungal membranes as well as $Trp^2$ and $Phe^5$ at the N-terminal helix play an important role in attracting cecropin-like peptides to the negatively charged bacterial cell membrane. Cecropin-like peptides can be potent peptide antibiotics against multi-drug resistant Gram negative bacteria and fungi.

• Korean Journal of Microbiology
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• v.33 no.3
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• pp.170-174
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• 1997

In order to design a novel synthetic peptide with improved fungicidal activity but low hemolytic activity, a hybrid peptide, cecropin A(l-8)-magainin 2(1-12), and its analogue peptides were synthesized by the solid phase method. Antifungal and hemolytic activities of the synthetic peptides were assessed by the growth inhibition against Trichosporon beigelii and the cell membrane lysis against human red hlood cells, respectively. Analogue 2 in which Lys at position 12 in cecropin A(1-8)-magainin 2(1-12) was substituted with Ala showed most potent antifungal activity (MIC: 2.5.$\mu$g/ml) with minimal hemolytic activity (0.5% hemolysis at the (200.$\mu$g/ml peptide). This peptide (A2), therefore, could be useful as a model for further designing potent antifungal peptides without cytotoxicity.

• Journal of Sericultural and Entomological Science
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• v.52 no.1
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• pp.45-51
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• 2014

A cecropin-A gene was isolated from the immunized larvae of the Japanese oak silkworm, Antheraea yamamai and designed Ay-CecA. The complete Ay-CecA cDNA consists of 419 nucleotides with 195 bp open reading frame encoding a 64 amino acid precursor that contains a putative 22-residue signal peptide, a 4-residue propetide and a 37-residue mature peptide with a theoretical mass of 4046.81. The deduced amino acid sequence of the peptide evidenced a significant degree of identity (62 ~ 78% identity) with other lepidopteran cecropins. Like many insect cecropin, Ay-CecA also harbored a glycine residue for C-terminal amidation at the C-end, which suggests potential amidation. To understand this peptide better, we successfully expressed bioactive recombinant Ay-CecA in Escherichia coli that are highly sensitive to the mature peptide. For this, we fused mature Ay-CecA gene with insoluble protein ketosteroid isomerase (KSI) gene to avoid the cell death during induction. The fusion KSI-CecA protein was expressed as inclusion body. The expressed fusion protein was purified by Ni-NTA immobilized metal affinity chromatography (IMAC), and cleaved by cyanogen bromide (CNBr) to release recombinant Ay-CecA. The purified recombinant Ay-CecA showed considerably antibacterial activity against Gram-negative bacteria, E. cori ML 35, Klebsiella pneumonia and Pseudomonas aeruginosa. Our results proved that this peptide with a potent antibacterial activity may play a role in the immune response of Japanese oak silkworm.

• Journal of Veterinary Science
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• v.22 no.5
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• pp.59.1-59.13
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• 2021

Background: Antimicrobial peptides (AMPs) have been identified as promising compounds for consideration as novel antimicrobial agents. Objectives: This study analyzed the efficacy of cecropin B against Haemophilus parasuis isolates through scanning electron microscopy (SEM) and atomic force microscopy (AFM) experiments. Results: Cecropin B exhibited broad inhibition activity against 15 standard Haemophilus parasuis (HPS) strains and 5 of the clinical isolates had minimum inhibition concentrations (MICs) ranging from 2 to 16 ㎍/mL. Microelectrophoresis and hexadecane adsorption assays indicated that the more hydrophobic and the higher the isoelectric point (IEP) of the strain, the more sensitive it was to cecropin B. Through SEM, multiple blisters of various shapes and dents on the cell surface were observed. Protrusions and leakage were detected by AFM. Conclusions: Based on the results, cecropin B could inhibit HPS via a pore-forming mechanism by interacting with the cytoplasmic membrane of bacteria. Moreover, as cecropin B concentration increased, the bacteria membrane was more seriously damaged. Thus, cecropin B could be developed as an effective anti-HPS agent for use in clinical applications.

• BMB Reports
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• v.31 no.6
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• pp.536-541
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• 1998

The cDNA clone encoding the antibacterial peptide (SL-1) was isolated from the fat body of the common cutworm, Spodoptera litura, immunized with E. coli K12. The primary structure analysis revealed that its deduced amino acid sequence showed the characteristics of the cecropin family antibacterial peptides and that the amino acid residues highly conserved in the antibacterial peptides from moths and flies were also conserved, implying that SL-1 was a cecropin-like, and especially cecropin B-like, peptide. The predicted secondary structure of the mature SL-1 consists of three domains: (i) an amphiphilic ${\alpha}$-helical domain (Ile-4 to Gly-18); (ii) the hinge region (Gly-23 and Pro-24); and (iii) a hydrophobic domain (Ala-25 to IIe-38).

• International Journal of Industrial Entomology and Biomaterials
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• v.37 no.2
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• pp.95-99
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• 2018

In insect defense system, antimicrobial peptides (AMPs) are one of important biological molecules to survive in a variety of environments. Insect can synthesize AMPs to protect against invading pathogens in humoral immune response. Taking more advantage of biological antimicrobial molecules, we report antibacterial activity of two cecropin type peptides, cecropin and moricin, isolated from the silkworm against four salmonella species. In this work, we purified antimicrobial candidate peptides (AMCP) from the extracts of immune challenged silkworm larval hemolymph by two-step chromatographic purification procedure, cation exchange and gel permeation chromatography. The molecular weights of purified peptides were estimated to be about 4 ~ 5 kDa by Tricin SDS-PAGE analysis, and identified as silkworm cecropin and moricin by NCBI BLAST homology search with their N-terminal amino acid sequences. As antibacterial activity assay, the purified peptides showed stronger antibacterial activity against Salmonella pathogens with an MIC value of $1{\sim}4{\mu}g/mL$. Therefore two cecropin type peptides purified from the silkworm will be valuable potential materials for development of new natural antibiotics.

• Journal of Microbiology and Biotechnology
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• v.9 no.2
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• pp.168-172
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• 1999

The antifungal mechanism of the antifungal peptide against Aspergillus fumigatus, $K^{18,19}$-CA(l-8)-ME(l-12), derived from cecropin A(l-8)-melittin(l-12) was investigated by confocal laser scanning microscopy, cell wall regeneration, ATPase activity inhibition, and released potassium ion. By confocal laser scanning microscopy, $K^{18,19}$-CA(l-8)-ME(l-12) was detected on the surface of A. fumigatus, while cecropin A used as a negative control peptide was not detected. The protoplast of A. fumigatus treated with$K^{18,19}$-CA(1-8)-ME(1-12) failed to regenerate the fungal cell walls. Compared with cecropin A, the amount of potassium ion released by $K^{18,19}$-CA(l-8)-ME(l-12) was increased. Furthermore, $K^{18,19}$-CA(l-8)-ME(l-12) inhibited the ATPase activity on the plasma membrane. These results suggested that $K^{18,19}$-CA(l-8)-ME(1-12) acts on the plasma membrane of A. fumigatus and its antifungal action is due to the ion channel or pore formation on the plasma membrane.

• Proceedings of the Korean Biophysical Society Conference
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• 1999.06a
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• pp.32-32
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• 1999

Cecropin A(1-8)-magainin 2(1-12) and cecropm A(1-8)-melittin(1-12) hybrid peptides were known to have potent antitumor and antibacterial activity. In particular, cecropm A(l-8)-magainin 2(1-12) has powerful antibacterial and antitumor activity with no hemolytic effect.(omitted)