• 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.

• 한국축산식품학회지
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• 제38권5호
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• pp.1064-1079
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• 2018

In this study, the antimicrobial activity of a bacteriocin produced by Enterococcus faecalis KT11, isolated from traditional Kargı Tulum cheese, was determined, and bacteriocin KT11 was partially characterized. The results showed that bacteriocin KT11 was antagonistically effective against various Gram-positive and Gram-negative test bacteria, including vancomycin- and/or methicillin-resistant bacteria. The activity of bacteriocin KT11 was completely abolished after treatment with proteolytic enzymes (proteinase K, ${\alpha}$-chymotrypsin, protease and trypsin), which demonstrates the proteinaceous nature of this bacteriocin. Additionally, bacteriocin KT11 remained stable at pH values ranging from 2 to 11 and after autoclaving at $121^{\circ}C$ for 30 min. In addition, the activity of bacteriocin KT11 was stable after treatment with several surfactants (EDTA, SDS, Triton X-100, Tween 80 and urea) and organic solvents (chloroform, propanol, methanol, ethyl alcohol, acetone, hexane and ethyl ether). Cell-free supernatant of E. faecalis KT11 was subjected to ammonium sulfate precipitation and then desalted by using a 3.5-kDa cut-off dialysis membrane. The bacteriocin activity was determined to be 711 AU/mL in the dialysate. After tricine-SDS-PAGE analysis, one peptide band, which had a molecular weight of ~3.5 kDa, exhibited antimicrobial activity. Because the bacteriocin KT11, isolated from E. faecalis KT11, exhibits a broad antimicrobial spectrum, heat stability and stability over a wide pH range, this bacteriocin can be used as a potential bio-preservative in foods. Additionally, bacteriocin KT11 alone or in combination with conventional antibiotics may provide a therapeutic option for the treatment of multidrug-resistant clinical pathogens after further in vivo studies.

• 약학회지
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• 제55권3호
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• pp.227-233
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• 2011

We previously reported the protein isolated from Coptidis Rhizoma (CRP), which has antifungal activity against a fungal pathogen, Candida albicans. In the current study, we investigated what portion in the CRP is responsible for the antifungal activity. For the investigation, the CRP was fractionated on a Shepadex G-50 column. Data resulting from the fractionation, seven fractions were obtained. Fractions (Fr.) I, II, and III eluted initially from the column showed no inhibitory effect on the growth of C. albicans, whereas Fr. IV, V, and VI eluted later revealed inhibition of the growth, and Fr. IV and VI showed potent antifungal activity by broth susceptibility analysis. However, Fr. VI was contained in the CRP more than Fr. IV, which led us to select the VI for the following experiments. In a murine model of a subcutaneous candidiasis caused by C. albicans, the Fr. VI displayed a therapeutic effect on nude mice pretreated with anti-neutrophil monoclonal antibody (RB68C5) and then infected subcutaneously with live C. albicans. At day 16, these mice were healed almost up to 78% of the infected area when compared to infected area of control nude mice that received diluent (Dulbecco's Phosphate-Buffered Saline; DPBS), instead of the Fr. VI (P<0.01). The Fr. VI blocked hyphal formation from blastoconidial form of C. albicans (P<0.01), which might prevent penetration of hyphae to the deeper site of skin and thus helps the healing. In the ionic strength test, the effect of Fr. was influenced by $Ca^{2+}$ ion just like other known antimicrobial peptides, but the influence was affected at an extremely high concentration such as 500 mM. Thus, such ion-concentration is considered to be meaningless in the clinical situation. Considering all data together, Coptidis Rhizoma is appeared to produce an antimicrobial peptide that has therapeutic effect on subcutaneous infection caused by C. albicans.

• 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.

• Asian-Australasian Journal of Animal Sciences
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• 제31권9호
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• pp.1516-1524
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• 2018

Objective: Defensins are a large family of antimicrobial peptides and components of the innate immune system that invoke an immediate immune response against harmful pathogens. Defensins are classified into alpha-, beta-, and theta-defensins. Avian species only possess beta-defensins (AvBDs), and approximately 14 AvBDs (AvBD1-AvBD14) have been identified in chickens to date. Although substantial information is available on the conservation and phylogenetics, limited information is available on the expression and regulation of AvBD8 in chicken immune tissues and cells. Methods: We examined AvBD8 protein expression in immune tissues of White Leghorn chickens (WL) by immunohistochemistry and quantitative reverse transcription-polymerase chain reaction (RT-qPCR). In addition, we examined AvBD8 expression in chicken T-, B-, macrophage-, and fibroblast-cell lines and its regulation in these cells after lipopolysaccharide (LPS) treatment by immunocytochemistry and RT-qPCR. Results: Our results showed that chicken AvBD8 protein was strongly expressed in the WL intestine and in macrophages. AvBD8 gene expression was highly upregulated in macrophages treated with different LPS concentrations compared with that in T- and B-cell lines in a time-independent manner. Moreover, chicken AvBD8 strongly interacted with other AvBDs and with other antimicrobial peptides as determined by bioinformatics. Conclusion: Our study provides the expression and regulation of chicken AvBD8 protein in immune tissues and cells, which play crucial role in the innate immunity.

• 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.

• Bulletin of the Korean Chemical Society
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• 제20권9호
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• pp.1078-1084
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• 1999

A synthetic cecropin A(1-13)-melittin(1-13) [CA-ME] hybrid peptide was known to be an antimicrobial peptide having strong antibacterial, antifungal and antitumor activity with minimal cytotoxic effect against human erythrocyte. Analogues were synthesized to investigate the influences of the flexible hinge region of CA-ME on the antibiotic activity. Antibiotic activity of the peptides was measured by the growth inhibition against bac-terial, fungal and tumor cells and vesicle-aggregating or disrupting activity. The deletion of Gln-Gly-Ile (P1) or Gly-Gln-Gly-Ile-Gly (P3) from CA-ME brought about a significant decrease on the antibiotic activities. In contrast, Gly-Ile-Gly deletion (P2) from CA-ME or Pro insertion (P5) instead of Gly-Gln-Gly-Ile-Gly of CA-ME retained antibiotic activity. This result indicated that the flexible hinge or β-bend structure provided by Gly-Gln-Gly-Ile-Gly, Gln-Gly, or Pro in the central region of the peptides is requisite for its effective antibiotic activity and may facilitate easily the hydrophobic C-terminal region of the peptide to penetrate the lipid bilayers of the target cell membrane. In contrast, P4 and P6 with Gly-Gln-Gly-Pro-Gly or Gly-Gln-Pro in the central region of the peptide caused a drastic reduction on the antibiotic activities. This result suggested that the con-secutive β-bend structure provided by Gly-Gln-Gly-Pro-Gly or Gly-Gln-Pro in the central hinge region of the peptide seems to interrupt the ion channel/pore formation on the target cell membranes.

• 한국축산식품학회지
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• 제41권6호
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• pp.967-982
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• 2021

Probiotics are living microorganisms that, when administered in adequate amounts, provide a health benefit to the host and are considered safe. Most probiotic strains that are beneficial to human health are included in the "Lactic acid bacteria" (LAB) group. The positive effects of probiotic bacteria on the host's health are species-specific and even strain-specific. Therefore, evaluating the probiotic potential of both wild and novel strains is essential. In this study, the probiotic characteristics of Lactobacillus brevis KT38-3 were determined. The strain identification was achieved by 16S rRNA sequencing. API-ZYM test kits were used to determine the enzymatic capacity of the strain. L. brevis KT38-3 was able to survive in conditions with a broad pH range (pH 2-7), range of bile salts (0.3%-1%) and conditions that simulated gastric juice and intestinal juice. The percentage of autoaggregation (59.4%), coaggregation with E. coli O157:H7 (37.4%) and hydrophobicity were determined to be 51.1%, 47.4%, and 52.7%, respectively. L. brevis KT38-3 produced β-galactosidase enzymes and was able ferment lactose. In addition, this strain was capable of producing antimicrobial peptides against the bacteria tested, including methicillin and/or vancomycin-resistant bacteria. The cell-free supernatants of the strain had high antioxidant activities (DPPH: 54.9% and ABTS: 48.7%). Therefore, considering these many essential in vitro probiotic properties, L. brevis KT38-3 has the potential to be used as a probiotic supplement. Supporting these findings with in vivo experiments to evaluate the potential health benefits will be the subject of our future work.

• The Korean Journal of Physiology and Pharmacology
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• 제26권4호
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• pp.287-295
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• 2022

Staphylococcus aureus (S. aureus) is known to induce apoptosis of host immune cells and impair phagocytic clearance, thereby being pivotal in the pathogenesis of atopic dermatitis (AD). Adipose-derived stem cells (ASCs) exert therapeutic effects against inflammatory and immune diseases. In the present study, we investigated whether systemic administration of ASCs restores the phagocytic activity of peripheral blood mononuclear cells (PBMCs) and decolonizes cutaneous S. aureus under AD conditions. AD was induced by injecting capsaicin into neonatal rat pups. ASCs were extracted from the subcutaneous adipose tissues of naïve rats and administered to AD rats once a week for a month. Systemic administration of ASCs ameliorated AD-like symptoms, such as dermatitis scores, serum IgE, IFN-γ⁺/IL-4⁺ cell ratio, and skin colonization by S. aureus in AD rats. Increased FasL mRNA and annexin V⁺/7-AAD⁺ cells in the PBMCs obtained from AD rats were drastically reversed when co-cultured with ASCs. In contrast, both PBMCs and CD163⁺ cells bearing fluorescent zymosan particles significantly increased in AD rats treated with ASCs. Additionally, the administration of ASCs led to an increase in the mRNA levels of antimicrobial peptides, such as cathelicidin and β-defensin, in the skin of AD rats. Our results demonstrate that systemic administration of ASCs led to decolonization of S. aureus by attenuating apoptosis of immune cells in addition to restoring phagocytic activity. This contributes to the improvement of skin conditions in AD rats. Therefore, administration of ASCs may be helpful in the treatment of patients with intractable AD.

• 한국식품저장유통학회지
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• 제13권1호
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• pp.88-94
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• 2006

단백 효소 가수분해물의 천연 항균제로서의 응용성을 검토하기 위하여 casein에 5종의 단백질 가수분해 효소를 작용시켜 얻어진 가수 분해물의 항균활성을 측정하고 활성이 가장 높은 가수분해물을 부분 정제하여 그 응용성을 검토하였다. Casein에 5종 단백질 분해효소를 작용시켜 얻은 가수분해물의 항균활성은 Aspergillus oryzae protease에 의한 것이 가장 높았다. 효소처리에 의하여 얻어진 가수분해 물을 30,000, 10,000, 3,000 membrane filter로 한외여과 하였을 때 항균활성은 3,000이하 분획물에 대부분 함유되어 있었으며 공시균주에 대한 최소저해농도는 $1.0\~1.5\;mg/mL$이었다. Aspergillus oryzae pretense로 작용시킨 casein 가수분해물은 $121^{\circ}C$에서 10분간 가열했을 때도 그 항균 활성을 유지하는 것으로 보아 열에 안정하였다. 가수분해물을 HPLC로 220 nm 280 nm에서 검출된 peak 별로 수집하여 항균활성을 측정 한 결과 retention time 12.6, 13.2 분에서 분취된 peptide가 활성이 있었다. 가수분해 동결건조물을 된장에 첨가하였을 때 미생물의 생육이 저해되었으며 실용성이 있었다.