• 한국자기공명학회논문지
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• 제2권2호
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• pp.120-130
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• 1998

• 한국자기공명학회:학술대회논문집
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• 한국자기공명학회 1999년도 동계총회 및 제14회 자기공명 학술발표회
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• pp.13-13
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• 1999

• 한국미생물·생명공학회지
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• 제25권3호
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• pp.335-337
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• 1997

In this study, we show a convenient MTT assay for detect the susceptibility of yeast-like form of Trichosporon beigelii against antifungal agents. This assay was developed based on mitocondrial respiration by determining reduction of 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) to formazan. Cells of T beigelii are seeded into 96-well microtiter plates, and antifungal agents, amphotericin B, magainin and CA-ME hybrid peptide were added with various concentrations. After 24 hr incubation, MTT was added, then incubations were continued for 4 hr. Formazan formation was quantified photometrically after extraction of the formazan with acid sodium dodesyl sulfate (SDS). From this assay, we could obtained MICs of antifungal agents against T. beigelii. The presented method can easily be used as an effective methods to assess the antiftingal action of various agents on yeasts with minimal amounts of antifungal agents.

• Bulletin of the Korean Chemical Society
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• 제24권3호
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• pp.369-376
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• 2003

Coulson (ZINDO), Mulliken $(MP2/6-31G^*)$ and Natural $(MP2/6-31G^*)$ population analyses of several large molecules were performed by the Fragment Reassociation (FR) method. The agreement between the conventional ZINDO (or conventional MP2) and FR-ZINDO (or FR-MP2) charges of these molecules was excellent. The standard deviations of the FR-ZINDO net atomic charges from the conventional ZINDO net atomic charges were 0.0008 for $C_{10}H_{22}$ (32 atoms), 0.0012 for $NH_2-C_{16}O_2H_{28}-COOH$ (53 atoms), 0.0014 for $NH_3^+-C_{16}O_2H_{28}-COOH$ (54 atoms), 0.0017 for $NH_2-C_{16}O_2H_{28}-COO^-$ (52 atoms), 0.0019 for $NH_3^+-C_{16}O_2H_{28}-COO^-$ (53 atoms), 0.0024 for a conjugated model $(O=CH-(CH=CH)_{15}-C=O-(CH=CH)_{12}-CH=CH_2)$, 118 atoms), 0.0038 for aglycoristocetin $(C_{60}N_7O_{19}H_{52}^+$, 138 atoms), 0.0023 for a polypropylene model complexed with a zirconocene catalyst $(C_{68}H-{121}Zr^+$, 190 atoms) and 0.0013 for magainin $(C_{112}N_{29}O_{28}SH_{177}$, 347 atoms), respectively. The standard deviations of the FR-MP2 Mulliken (or Natural) partial atomic charges from the conventional ones were 0.0016 (or 0.0016) for $C_{10}H_{22}$, 0.0019 (or 0.0018) for $NH_2-C_{16}O_2H_{28}-COOH$ and 0.0033 (or 0.0023) for $NH_3^+-C_{16}O_2H_{28}-COO^-$, respectively. These errors were attributed to the shape of molecules, the choice of fragments and the degree of ionic characters of molecules as well as the choice of methods. The CPU time of aglycoristocetin, conjugated model, polypropylene model complexed with zirconocene and magainin computed by the FR-ZINDO method was respectively 2, 4, 6 and 21 times faster than that by the normal ZINDO method. The CPU time of $NH_2-C_{16}O_2H_{28}-COOH\;and\;NH_3^+-C_{16}O_2H_{28}-COO^-$ computed by the FR-MP2 method was, respectively, 6 and 20 times faster than that by the normal MP2 method. The largest molecule calculated by the FR-ZINDO method was B-DNA (766 atoms). These results will enable us to compute atomic charges of huge molecules near future.

• 한국미생물·생명공학회지
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• 제35권4호
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• pp.278-284
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• 2007

생체 염 농도에서도 항균활성을 유지할 수 있는 선형 ${\alpha}$-helical 항균 펩타이드를 M13 펩타이드 라이브러리로부터 탐색할 수 있는 새로운 방법을 개발하였다. M13의 pIII은 magainin 유도체인 MSI-344와 indolicidin과 융합된 상태에서도 파아지의 viability에 영향을 주지 않는 것으로 보아, MSI-344와 indolicidin의 대장균에 대한 독성을 중화할 수 있는 것으로 판단되며, 따라서 대장균에서 항균 펩타이드 라이브러리의 제조가 가능함을 증명하였다. 선형 항균 펩타이드의 보존된 부위를 바탕으로, 13개의 아미노산 잔기로 구성된 semi-combinatorial 항균 펩타이드 라이브러리를 M13를 이용하여 제조하였다. 제조된 파아지 라이브러리는 먼저 적혈구에 흡착시켜, 높은 용혈 역가를 가질 가능성이 있는 파아지를 제거한 후, 높은 염 농도에서 Pseudomonas aeruginosa와 Staphylococcus aureus에 흡착할 수 있는 파아지를 탐색하였다. 탐색된 펩타이드들은 염이 없는 조건에서는 비교적 낮은 항균 역가를 보였지만, P06와 S18 펩타이드의 경우, 생체 염 농도보다 높은 150 mM $Na^+$, 2 mM $Mg^{2+}$, 2 mM $Ca^{2+}$의 조건에서도 항균 역가가 영향을 받지 않았으며, 심각한 용혈 역가 또한 보이지 않았다. 본 연구에서 개발한 대상 세균에 대한 흡착능력을 이용한 탐색방법은 salt-tolerant antimicrobial peptide의 개발의 새로운 가능성을 제시하였다.

• 통합자연과학논문집
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• 제1권1호
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• pp.47-53
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• 2008

In a previous study, we showed that Cecropin A (1-8)-Magainin 2 (1-12) hybrid peptide (CA-MA)'s analogue, Anal P5, exhibit broad-spectrum antimicrobial activity. Anal P5, designed by flexible region (positions 9, 10)-substitution, Lys- (positions 4, 8, 14, 15) and Leu- (positions 5, 6, 12, 13, 16, 17, 20) substitutions, showed an enhanced antimicrobial and antitumor activity without hemolysis. The primary objective of the present study was to gain insight into the relevant mechanisms of antimicrobial activities of Anal P5 by using flow cytometric analysis. Anal P5 exhibits strong antifungal activity in a salt concentration independent manner. In addition, Anal P5 causes significant morphological alterations of the bacterial surfaces as shown by scanning electron microscopy, supporting its antibacterial activity. Its potent antibiotic activity suggests that Anal P5 is an excellent candidate as a lead compound for the development of novel antibiotic agents.

• 한국미생물·생명공학회지
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• 제24권5호
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• pp.529-533
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• 1996

Melittin (ME) from honeybee venom has a broad range of strong antimicrobial activity, but it has hemolytic activity against eukaryotic cells. In order to design peptides with powerful antifungal activity without cytotoxic property of ME and understand structure-antifungal activity relationships, the hybrid peptides derived from the sequences of ME and cecropin A (CA) or magainin 2 (MA), MA(10-17)ME(1-12) and CA(1-8)ME(1-12). were synthesized by solid phase method. MA(10-17)ME(1-12) showed potent antifungal activity comparable to ME against Fusarium oxysporum with no hemolytic activity against human red blood cells. The hybrid peptides showed strong inhibi- tion of (1, 3)-$\beta$-D-glucan synthase. This result indicates that the antifungal activity of the hybrid peptides against Fusarium oxysporum is attributed to the inhibition of cell wall synthesis. The results therefore showed a successful design of a peptide having antifungal activity without hemolytic property.

• Bulletin of the Korean Chemical Society
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• 제30권8호
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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.

• 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
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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.