Anzai K, Hamasuna M, Kadono H, Lee S, Aoyagi H, Kirino Y
Faculty of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan.
Biochim Biophys Acta. 1991 May 7;1064(2):256-66. doi: 10.1016/0005-2736(91)90310-5.
We made use of a planar lipid bilayer system to examine the action of synthetic basic peptides which model the prepiece moiety of mitochondrial protein precursors and have antibacterial activity against Gram-positive bacteria. The sequences of the peptides used were as follows: Ac-(Ala-Arg-Leu)3-NHCH3 (3(3], Ac-(Leu-Ala-Arg-Leu)2-NHCH3 (4(2], Ac-(Leu-Ala-Arg-Leu)3-NHCH3 (4(3], Ac-(Leu-Leu-Ala-Arg-Leu)2-NHCH3 (5(2]. These peptides interacted differently with planar lipid bilayer membranes and membrane conductance increased by the formation of ion channels. The effects of the peptides on the macroscopic current-increase and on the probability of channel formation, at the single channel level were in the order of 4(3) greater than 4(2) approximately 5(2) much greater than 3(3), a finding which correlates with the antibacterial activity of these peptides. The micromolar (microM) order concentration at which the channel was formed resembles that causing antibacterial activity. Thus, the peptide antibacterial activity may occur through an increase in ion permeability of the bacterial membrane. The single-channel properties were investigated in detail using 4(3), the peptide with the highest ion channel-forming activity. Many types of channels were observed with respect to conductance (2-750 pS) and voltage dependency of gating. However, the channels were all cation-selective. These results suggest that the ion channels formed by peptide 4(3) may be able to take on a variety of conformations and/or assembly.
我们利用平面脂质双层系统来研究合成碱性肽的作用，这些肽模拟线粒体蛋白前体的前肽部分，并对革兰氏阳性菌具有抗菌活性。所用肽的序列如下：Ac-(Ala-Arg-Leu)3-NHCH3 (3(3])、Ac-(Leu-Ala-Arg-Leu)2-NHCH3 (4(2])、Ac-(Leu-Ala-Arg-Leu)3-NHCH3 (4(3])、Ac-(Leu-Leu-Ala-Arg-Leu)2-NHCH3 (5(2])。这些肽与平面脂质双层膜的相互作用不同，并且通过离子通道的形成使膜电导增加。在单通道水平上，这些肽对宏观电流增加和通道形成概率的影响顺序为4(3)大于4(2)，约5(2)远大于3(3)，这一发现与这些肽的抗菌活性相关。形成通道的微摩尔（μM）级浓度与引起抗菌活性的浓度相似。因此，肽的抗菌活性可能是通过细菌膜离子通透性的增加而产生的。使用离子通道形成活性最高的肽4(3)详细研究了单通道特性。观察到了许多类型的通道，其电导范围为2 - 至750 pS，且门控具有电压依赖性。然而，所有通道均具有阳离子选择性。这些结果表明，由肽段4(3)形成的离子通道可能能够呈现多种构象和/或组装形式。
