• 생명과학회지
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• 제26권6호
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• pp.737-748
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• 2016

현재까지 곤충 항균 펩티드는 1980년에 세크로피아나방(Hyalophora cecropia) 번데기의 혈림프로부터 세크로핀(cecropin)이 처음으로 정제된 이후로 150개 이상의 펩티드가 분리되어 특성들이 보고되어 왔다. 그러므로 곤충은 항균 펩티드 선발을 위한 좋은 재료로서 고려되어 왔다. 곤충 항균 펩티드는 분자량이 작으며 양전하를 띠고 다양한 길이와 서열 및 구조를 갖는 양친매성의 특징을 갖는다. 곤충 항균 펩티드는 박테리아, 진균, 기생충, 그리고 바이러스와 같은 병원체들의 침입에 대항하여 곤충의 선천성 면역체계에서 중요한 역할을 수행한다. 대부분의 곤충 항균 펩티드들은 상처가 나거나 면역화 시 지방체와 다른 특정 조직들에서 유도 합성된다. 이어서 그 항균 펩티드들은 미생물들에 대항하여 작용하기 위해 혈림프로 분비되어 나온다. 이들 펩티드들은 항암활성을 포함하여 다양한 미생물들에 대해 광범위한 항균활성을 나타낸다. 곤충 항균 펩티드는 구조 및 서열상의 특징들에 기초하여 크게 4개의 패밀리로 나누어질 수 있다. 다시 말해서 α-나선형 펩티드, 시스테인-풍부 펩티드, 프롤린-풍부 펩티드, 그리고 글리신-풍부 펩티드/단백질이 그것이다. 예를 들면, 세크로핀, 곤충 디펜신(defensin), 프롤린-풍부 펩티드, 그리고 아타신(attacin)이 일반적인 곤충 항균 펩티드들인데, 글로베린(gloverin)과 모리신(moricin)은 나비목 종들에서만 확인되어 왔다. 본 총설에서는 곤충의 항균 펩티드들에 초점을 맞추어 곤충 항균 펩티드들의 적용 가능성 및 방향과 함께 현재의 지식들과 최근의 진전된 사항들에 대하여 논의하고자 한다.

• 생명과학회지
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• 제24권8호
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• pp.860-864
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• 2014

별불가사리(Asterina pectinifera)의 유문 맹낭 추출물로부터 새로운 항균활성 펩타이드를 정제하기 위해서 유문 맹낭 추출물을 역상 HPLC와 이온 HPLC column에 주입하였다. 강한 항균활성을 나타내는 2개의 새로운 펩타이드가 유문 맹낭 추출물로부터 정제되었다. 이러한 물질들은 Pyloric caeca Asterina pectinifera peptides (PAP-1와 PAP-2)라 명명하였다. 정제한 물질들의 특성을 알아보기 위해서, 분자량 및 아미노산 서열 분석은 MALDI-TOF 질량분석기와 에드만 분해법으로 조사하였다. PAP-1과 PAP-2의 분자량은 각각 약 2952 Da 및 2980 Da이었다. PAP-1과 PAP-2의 부분적인 N-말단 서열은 다음과 같다. PAP-1, AIQNAGES; PAP-2, AIQNAAES. PAP-2는 PAP-1의 6번째 위치(glycine or alanine)에서 한 잔기만 다른 isoform에 해당된다. 지금까지 밝혀진 항균활성 펩타이드와의 분자량 및 N-말단 아미노산 서열을 비교한 결과, 이들 물질들은 다른 물질들과 동일성을 나타내지 않았다. 이러한 발견은 PAP-1과 PAP-2가 별불가사리의 유문맹낭의 선천성 방어계에 중요한 역할을 담당하고 있는 것을 시사하고 있다.

• BMB Reports
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• 제38권5호
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• pp.507-516
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• 2005

Antimicrobial peptides (AMPs) have been isolated and characterized from tissues and organisms representing virtually every kingdom and phylum. Their amino acid composition, amphipathicity, cationic charge, and size allow them to attach to and insert into membrane bilayers to form pores by 'barrel-stave', 'carpet' or 'toroidal-pore' mechanisms. Although these models are helpful for defining mechanisms of AMP activity, their relevance to resolving how peptides damage and kill microorganisms still needs to be clarified. Moreover, many AMPs employ sophisticated and dynamic mechanisms of action to carry out their likely roles in antimicrobial host defense. Recently, it has been speculated that transmembrane pore formation is not the only mechanism of microbial killing by AMPs. In fact, several observations suggest that translocated AMPs can alter cytoplasmic membrane septum formation, reduce cell-wall, nucleic acid, and protein synthesis, and inhibit enzymatic activity. In this review, we present the structures of several AMPs as well as models of how AMPs induce pore formation. AMPs have received special attention as a possible alternative way to combat antibiotic-resistant bacterial strains. It may be possible to design synthetic AMPs with enhanced activity for microbial cells, especially those with antibiotic resistance, as well as synergistic effects with conventional antibiotic agents that lack cytotoxic or hemolytic activity.

• BMB Reports
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• 제29권6호
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• pp.545-548
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• 1996

CA(1-8)ME(1-12), the CA-ME hybrid peptide of the amino terminal segments of cecropin A (CA) and melittin (ME), has been reported to have a broad spectrum and improved potency without a hemolytic property. In order to obtain new synthetic peptides with powerful antibacterial activity without hemolytic activity, several hybrid peptides were designed from the sequences of CA, ME, magainin 2, bombinin and lactoferricin. All hybrid peptides were constructed to form an amphipathically basic-flexible-hydrophobic structure and synthesized by the solid phase method. Their hemolytic activities against human red blood cells and antibacterial activities against both Gram-positive and Gram-negative bacteria were detennined. CA(1-8)MA(1-12), CA(1-8)BO(1-12), MA(10-17)ME(1-12) and LF(20-29)ME(1-12) showed comparable activities with broad spectra against both Gram-positive and Gram-negative bacteria relative to CA(1-8)ME(1-12) but without hemolytic properties. These hybrid peptides, therefore, could be useful as model peptides to design a novel peptide with improved antibacterial activity and study on structure-activity relationships of antimicrobial peptides.

• Journal of Microbiology and Biotechnology
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• 제16권9호
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• pp.1429-1433
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• 2006

Application of recombinant protein production and particularly their isotopic enrichment has stimulated development of a range of novel multidimensional heteronuclear NMR techniques. Peptides in most cases are amenable to assignment and structure determination without the need for isotopic labeling. However, there are many cases where the availability of $^{15}N$ and/or $^{13}C$ labeled peptides is useful to study the structure of peptides with more than 30 residues and the interaction between peptides and membrane. CRAMP (Cathelicidin-Related AntiMicrobial Peptide) was identified from a cDNA clone derived from mouse femoral marrow cells as a member of cathelicidin-derived antimicrobial peptides. CRAMP was successfully expressed as a GST-fused form in E. coli and purified using affinity chromatography and reverse-phase chromatography. The yield of the CRAMP was 1.5 mg/l 1. According to CD spectra, CRAMP adopted ${\alpha}$-helical conformation in membrane-mimetic environments. Isotope labeling of CRAMP is expected to make it possible to study the structure and dynamic properties of CRAMP in various membrane systems.

• Journal of Microbiology and Biotechnology
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• 제24권2호
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• pp.160-167
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• 2014

Oligopeptidase B (OpdB) is a serine peptidase widespread among bacteria and protozoa that has emerged as a virulence factor despite its function has not yet been precisely established. By using an OpdB-overexpressing Escherichia coli strain, we found that the overexpressed peptidase makes the bacterial cells specifically less susceptible to several proline-rich antimicrobial peptides known to penetrate into the bacterial cytosol, and that its level of activity directly correlates with the degree of resistance. We established that E. coli OpdB can efficiently hydrolyze in vitro cationic antimicrobial peptides up to 30 residues in length, even though they contained several prolines, shortening them to inactive fragments. Two consecutive basic residues are a preferred cleavage site for the peptidase. In the case of a single basic residue, there is no cleavage if proline residues are present in the $P_1$ and $P_2$ positions. These results also indicate that cytosolic peptidases may cause resistance to antimicrobial peptides that have an intracellular mechanism of action, such as the proline-rich peptides, and may contribute to define the substrate specificity of the E. coli OpdB.

• Journal of Microbiology and Biotechnology
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• 제29권11호
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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.

• Bulletin of the Korean Chemical Society
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• 제33권9호
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• pp.2883-2889
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• 2012

LL-37 is the only antimicrobial peptide (AMP) of the human cathelicidin family. In addition to potent antimicrobial activity, LL-37 is known to have the potential to inhibit lipolysaccharide (LPS)-induced endotoxic effects. To provide the stability to proteolytic digestion and increase prokaryotic selectivity and/or anti-endotoxic activity of two Lys/Trp-substituted 19-meric antimicrobial peptides (a4-W1 and a4-W2) designed from IG-19 (residues 13-31 of LL-37), we synthesized the diastereomeric peptides (a4-W1-D and a4-W2-D) with D-amino acid substitution at positions 3, 7, 10, 13 and 17 of a4-W1 and a4-W2, respectively and the enantiomeric peptides (a4-W1-E and a4-W2-E) composed D-amino acids. The diastereomeric peptides exhibited the best prokaryotic selectivity and effective protease stability, but no or less anti-endotoxic activity. In contrast, the enantiomeric peptides had not only prokaryotic selectivity and anti-endotoxic activity but also protease stability. Our results suggest that the hydrophobicity and ${\alpha}$-helicity of the peptide is important for anti-endotoxic activity. In particular, the enantiomeric peptides showed potent anti-endotoxic and LPS-neutralizing activities comparable to that of LL-37. Taken together, both a4-W1-E and a4-W2-E holds promise as a template for the development of peptide antibiotics for the treatment of endotoxic shock and sepsis.

• Journal of Microbiology and Biotechnology
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• 제25권6호
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• pp.759-764
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• 2015

Antimicrobial peptides (AMPs) are one of the critical components in host innate immune responses to imbalanced and invading microbial pathogens. Although the antimicrobial activity and mechanism of action have been thoroughly investigated for decades, the exact biological properties of AMPs are still elusive. Most AMPs generally exert the antimicrobial effect by targeting the microbial membrane, such as barrel stave, toroidal, and carpet mechanisms. Thus, the mode of action in model membranes and the discrimination of AMPs to discrepant lipid compositions between mammalian cells and microbial pathogens (cell selectivity) have been studied intensively. However, the latest reports suggest that not only AMPs recently isolated but also well-known membrane-disruptive AMPs play a role in intracellular killing, such as apoptosis induction. In this mini-review, we will review some representative AMPs and their antimicrobial mechanisms and provide new insights into the dual mechanism of AMPs.

• Biomolecules & Therapeutics
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• 제21권4호
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• pp.251-257
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• 2013

Inflammatory skin diseases such as atopic dermatitis (AD) and rosacea were complicated by barrier abrogation and deficiency in innate immunity. The first defender of epidermal innate immune response is the antimicrobial peptides (AMPs) that exhibit a broad-spectrum antimicrobial activity against multiple pathogens, including Gram-positive and Gram-negative bacteria, viruses, and fungi. The deficiency of these AMPs in the skin of AD fails to protect our body against virulent pathogen infections. In contrast to AD where there is a suppression of AMPs, rosacea is characterized by overexpression of cathelicidin antimicrobial peptide (CAMP), the products of which result in chronic epidermal inflammation. In this regard, AMP generation that is controlled by a key ceramide metabolite S1P-dependent mechanism could be considered as alternate therapeutic approaches to treat these skin disorders, i.e., Increased S1P levels strongly stimulated the CAMP expression which elevated the antimicrobial activity against multiple pathogens resulting the improved AD patient skin.