• Journal of Microbiology and Biotechnology
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• 제22권10호
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• pp.1367-1374
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• 2012

Pleurocidin, a 25-mer antimicrobial peptide, has been known to exhibit potent antibacterial activity. To investigate the functional roles in N- and C-terminal regions of pleurocidin on the antibacterial activity, we designed four truncated analogs. The antibacterial susceptibility testing showed that pleurocidin and its analogs exerted antibacterial effect against various bacterial strains and further possessed specific activity patterns corresponding with their hydrophobic scale [pleurocidin > Anal 3 (1-22) > Anal 1 (4-25) > Anal 4 (1-19) > Anal 2 (7-25)]. Fluorescence experiments using 1,6-diphenyl-1,3,5-hexatriene (DPH) and 3,3'-dipropylthiadicarbocyanine iodide [$diSC_3(5)$] indicated that the differences in antibacterial activity of the peptides were caused by its membrane-active mechanisms including membrane disruption and depolarization. Blue shift in tryptophan fluorescence demonstrated that the decrease in net hydrophobicity attenuates the binding affinity of pleurocidin to interact with plasma membrane. Therefore, the present study suggests that hydrophobicity in the N- and C-terminal regions of pleurocidin plays a key role in its antibacterial activity.

• International Journal of Industrial Entomology and Biomaterials
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• 제14권2호
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• pp.147-150
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• 2007

Abaecin is a largest member of the proline-rich anti-microbial peptide family found only in the hymenopterans. A cDNA of abaecin was previously isolated and cloned from Bombus ignitus: the mature peptide of Bombus ignitus abaecin was composed of 39 amino acid residues. In the present study, we determined the antibacterial effect of B. ignitus abaecin synthesized at several lengths against several bacteria by radial diffusion assay. The 37-mer peptide (Ab37) inhibited the growth of Gram-negative bacteria Escherichia coli ML-35, Pseudomonas aeruginosa and Salmonela typhimurium, but showed limited inhibitory activity toward Gram-positive bacteria, except for Micrococcus luteus. The truncated 26-mer peptide (Ab26), which was synthesized after truncating some amino acid residues at both N-terminus and C-terminus from the Ab37 peptide, still showed equivalent antibacterial activity to the Ab37. On the other hand, several further truncated peptides exhibited lower activity then did Ab37 peptide.

• 한국동물학회:학술대회논문집
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• 한국동물학회 1998년도 한국생물과학협회 학술발표대회
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• pp.244.2-244
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• 1998

No Abstract, See Full Text

• 한국동물학회:학술대회논문집
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• 한국동물학회 1998년도 한국생물과학협회 학술발표대회
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• pp.243.1-243
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• 1998

No Abstract, See Full Text

• Journal of Microbiology
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• 제35권1호
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• pp.21-24
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• 1997

The hybrid peptides, CA-ME, CA-MA and CA-BO, with the N-terminal sequence 1-8 of cecropin A and the N-terminal sequences 1-12 of melittin, magainin 2 and bombinin, respectively, have more improved antibacterial activities. CA-MA was found to have stronger antifungal activity against Trichoderma sp than other hybrid peptides and their parental peptides. In order to elucidate the relationships between the peptide structure and antifungal activity, several analogues of CA-MA or CA-BO were also designed and synthesized by the solid phase method. An tifungal activity was measured against T. reesei and T. viride, and hemolytic activity was measured by a solution method against human red blood cells. The residue 16 of CA-MA, Ser, was found to be important for antifungal activity. When the residue was substituted with Leu, showed powerful antifungal activity was dramatically decreased. CA-MA, P1, P4 and P5 designed in this study showed powerful antifungal activity against T. reesei and T. viride with low hemolytic activity against human red blood cells. These hybrid peptides will be potentially useful model to further design peptides with powerful antifungal activity for the effective therepy of fungal infection and understand the mechanisms of antifungal actions of hybrid peptides.

• Journal of Microbiology and Biotechnology
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• 제31권2호
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• pp.189-196
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• 2021

Periplanetasin-2 from cockroach exhibits broad-spectrum antimicrobial activity. The underlying antibacterial mechanisms rely on the stimulation of reactive oxygen species overproduction to induce apoptotic cell death. A promising strategy to increase the bioavailability of periplanetasin-2 involves reducing the dose through combination therapy with other antibacterials that show synergistic effects. Thus, the synergistic antibacterial activity of periplanetasin-2 with conventional antibacterial agents and its mechanisms was examined against Escherichia coli in this study. Among the agents tested, the combinations of periplanetasin-2 with vancomycin and chloramphenicol exhibited synergistic effects. Periplanetasin-2 in combination with vancomycin and chloramphenicol demonstrated antibacterial activity through the intracellular oxidative stress response. The combination with vancomycin resulted in the enhancement of bacterial apoptosis-like death, whereas the combination with chloramphenicol enhanced oxidative stress damage. These synergistic interactions of periplanetasin-2 can help broaden the spectrum of conventional antibiotics. The combination of antimicrobial peptides and conventional antibiotics is proposed as a novel perspective on treatments to combat severe bacterial infection.

• 한국축산식품학회지
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• 제36권4호
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• pp.452-457
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• 2016

Lactoferrin is a glycoprotein with various biological effects, with antibacterial activity being one of the first effects reported. This glycoprotein suppresses bacterial growth through bacteriostatic or bactericidal action. It also stimulates the growth of certain kinds of bacteria such as lactic acid bacteria and bifidobacteria. In this study, Asn-Leu-Asn-Arg was selected and chemically synthesized based on the partial sequences of bovine lactoferrin tryptic fragments. Synthetic Asn-Leu-Asn-Arg suppressed the growth of Pseudomonas fluorescens, P. syringae and Escherichia coli. P. fluorescens is a major psychrotrophic bacteria found in raw and pasteurized milk, which decreases milk quality. P. syringae is a harmful infectious bacterium that damages plants. However, synthetic Asn-Leu-Asn-Arg did not inhibit the growth of Lactobacillus acidophilus. It is expected that this synthetic peptide would be the first peptide sequence from the bovine lactoferrin C-lobe that shows antibacterial activity.

• Journal of Dairy Science and Biotechnology
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• 제41권3호
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• pp.113-125
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• 2023

In this study, we explored the synergistic effects of whey protein concentrate (WPC) and soybean protein components after fermentation with lactic acid bacteria isolated from kimchi, and identified several peptides with desirable physiological functions, proteolysis, and immune effects. Antioxidant activity was determined using 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid, 1,1-diphenyl-2-picrylhydrazyl, ferric-reducing antioxidant power, and hydroxyl radical scavenging assays, followed by cross-validation of the four antioxidant activities. These assays revealed that samples with a 8:2 and 9:1 whey to soy ratio possessed higher antioxidant activity than the control samples. Antibacterial potency testing revealed high antibacterial activity in the 9:1 and 8:2 samples. Cytotoxicity testing of samples using 3-(4, 5-dimethyl thiazol-2-yl)-2, 5-diphenyl tetrazolium bromide revealed that only the 10:0, 1:9, and 0:10 samples had <80% viable cells, indicating no significant cytotoxicity. Nitric oxide (NO) assays revealed that NO expression was reduced in 8:2, 5:5, and 0:10 protein ratio fermentations, indicating low inflammatory reaction stimulatory potential. Cytokine expression was confirmed using an enzyme-linked immunosorbent assay kit. The 8:2 sample had the lowest inflammatory cytokine (interleukin [IL]-1α, IL-6, and tumor necrosis factor-α) levels compared with the lipopolysaccharide-treated group. Amino acid profiling of the 8:2 sample identified 17 amino acids. These results suggest that inoculating and fermenting Lactobacillus plantarum DK203 and Lactobacillus paracasei DK209 with an 8:2 mixture of WPC and soybean protein releases bioactive peptides with excellent anti-inflammatory and antioxidant properties, making them suitable for functional food development.

• Bulletin of the Korean Chemical Society
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• 제35권9호
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• pp.2818-2824
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• 2014

Trp residue is considered as one of the important constituents in antimicrobial peptides (AMPs) as it presence secured good activities in many cases. However, it is preferable to be changed because of their sensitivity towards light. We have synthesized the short Trp-rich AMP Pac-525 and its analogues to investigate the possibility of His(chx) as possible replacement analogue for Trp in AMPs. Based on the assay result of the antibacterial activity including anti-MRSA activity, His(chx) is considered as good candidate for the Trp replacement. Through these study, we found that His(chx) had several merits to design therapeutic antimicrobial agents compare to Trp in terms of i) increasing antibacterial activity without hemolytic activity, ii) successful in designing the short peptide (only four residues), iii) having anti-MRSA activity, iv) overcoming the light sensitivity. Furthermore, transmission electron microscopy (TEM) and dye leakage experiments suggested that P11 and P16 containing His(chx) kill bacteria via forming pore/ion channels on bacterial cell membranes.

• International Journal of Industrial Entomology and Biomaterials
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• 제31권2호
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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.