• Journal of Microbiology and Biotechnology
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• 제8권6호
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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.

• 한국생물물리학회:학술대회논문집
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• 한국생물물리학회 1999년도 학술발표회 진행표 및 논문초록
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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)

• 미생물학회지
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• 제33권3호
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• pp.170-174
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• 1997

강한 항진균 활성을 나타내며, 낮은 적혈구 용혈활성을 갖는 새로운 합성 펩티드를 얻기 위하여 cecropin A(1-8)-magainin 2(1-12) 및 이들의 유사체들을 설계하고 이들을 고상법에 의하여 합성하였다. 합성 펩티드의 항진균 활성은 Trichosporon beigelii에 대한 성장억제능에 의하여 측정하였으며, 세포독성은 인간의 적혈구 세포에 대한 용혈활성에 의하여 측정하였다. 펩티드의 양쪽 친매성의 증가는 항진균활성보다는 적혈구 용혈황성에 큰 영향을 미쳤다. Cecropin A(1-8)-magainin 2(1-12)의 12번 아미노산이 Lys을 Ala으로 치환시킨 유사체 펩티드(A2)는 가장 강한 항진균활성(minimum inhibitory concentration : 2.5.$\mu$g/ml)을 나타내며 비교적 낮은 적혈구 용혈활성(200.$\mu$g/ml의 펩티드 농도에서 0.5% hemolysis를 나타냄)을 나타내었다. 따라서 A2의 펩티드는 세포독성을 갖지 않으며 강한 항진균 활성을 가지는 모델로서 유용하게 사용될 것이다.

• 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

• Journal of Microbiology and Biotechnology
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• 제9권2호
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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.

• Journal of Microbiology and Biotechnology
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• 제7권1호
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• pp.49-51
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• 1997

In order to obtain a hybrid synthetic peptide with a more potent antifungal activity than magainin-2 but without hemolytic activity, four hybrid peptides were designed from the sequences of magainin 2 and cecropin A and their antifungal activities against Trichosporon beigelii were investigated. The result showed that analogue 2 and 4 exhibited better antifungal activity against T. beigelii than magainin-2 but no hemolytic activities. The peptides, therefore, could be used as models for the development of potent antifungal 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.

• 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.

• 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.

• 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.