Suenaga M, Lee S, Park N G, Aoyagi H, Kato T, Umeda A, Amako K
Laboratory of Biochemistry, Faculty of Science, Fukuoka, Japan.
Biochim Biophys Acta. 1989 May 19;981(1):143-50. doi: 10.1016/0005-2736(89)90092-8.
We have studied the fusion of small unilamellar vesicles composed of egg PC and of a mixture of egg PC plus egg PA using various basic amphipathic peptides. Fusion was monitored by carboxyfluorescein leakage assay, light scattering, membrane intermixing assay, contents mixing assay and electron microscopy. Ac-(L-Leu-L-Ala-L-Arg-L-Leu)3-NHCH3 (peptide 4(3] and Ac-(L-Leu-L-Ala-L-Lys-L-Leu)3-NHCH3 (peptide 4'3), which have high hydrophobic moments, caused transformation of small unilamellar vesicles into larger and relatively homogeneous ones. Ac-(L-Leu-L-Leu-L-Ala-L-Arg-L-Leu)2-NHCH3 (5(2], which has medium hydrophobic moment, induced weak but appreciable fusion, while Ac-(L-Ala-L-Arg-L-Leu)3-NHCH3 (3(3] which has no helical structure did not show any fusion. However, peptides 4(3), 4'3 and 5(2) caused massive leakage of the contents from small unilamellar vesicles. These results indicated that interaction of the peptides with artificial membranes caused extensive perturbation of the lipid bilayer, followed by fusion. The fusogenic capacity of model basic peptides was correlated with the hydrophobic moment of each peptide when the peptides adopted an alpha-helical structure in the presence of acidic liposomes. Peptides 4(3) and 4'3 also showed weak fusogenic ability for neutral liposomes, while 5(2) and 3(3) showed no ability, suggesting that highly amphipathic peptides, such as 4(3), interact weakly but distinctly with neutral liposomes to fuse them.
我们使用了各种碱性两亲性肽，研究了由鸡蛋卵磷脂（egg PC）以及鸡蛋卵磷脂与鸡蛋磷脂酸（egg PA）混合物组成的小单层囊泡的融合情况。通过羧基荧光素泄漏测定、光散射、膜混合测定、内容物混合测定和电子显微镜来监测融合过程。具有高疏水矩的Ac-(L-亮氨酸-L-丙氨酸-L-精氨酸-L-亮氨酸)3-NHCH3（肽4(3)）和Ac-(L-亮氨酸-L-丙氨酸-L-赖氨酸-L-亮氨酸)3-NHCH3（肽4'3），可使小单层囊泡转变为更大且相对均匀的囊泡。具有中等疏水矩的Ac-(L-亮氨酸-L-亮氨酸-L-丙氨酸-L-精氨酸-L-亮氨酸)2-NHCH3（5(2)）诱导了微弱但明显的融合，而没有螺旋结构的Ac-(L-丙氨酸-L-精氨酸-L-亮氨酸)3-NHCH3（3(3)）未显示出任何融合现象。然而，肽4(3)、4'3和5(2)导致小单层囊泡内容物大量泄漏。这些结果表明，肽与人工膜的相互作用引起了脂质双层的广泛扰动，随后发生融合。当肽在酸性脂质体存在下呈α-螺旋结构时，模型碱性肽的融合能力与每种肽的疏水矩相关。肽4(3)和4'3对中性脂质体也显示出微弱的融合能力，而5(2)和3(3)则没有融合能力，这表明高度两亲性的肽，如4(3)，与中性脂质体的相互作用较弱但能明显使其融合。
