Rizzo V, Schwarz G, Voges K P, Jung G
Eur Biophys J. 1985;12(2):67-73. doi: 10.1007/BF00260429.
The peptides Boc-(L-Ala-Aib-L-Ala-Aib-L-Ala)n-OMe, with n = 2 (P10) and n = 4 (P20), have been synthesized as purely hydrophobic models of the antibiotic alamethicin, which is known to be a voltage-dependent pore former in membranes and is apparently alpha-helical in lipophilic media. These peptides were investigated in 1-octanol, a solvent which resembles the membrane environment. From dielectric dispersion studies quantitative information on the molecular shape and dipole moments could be derived. Further independent data concerning conformation and extent of aggregation of the peptides were obtained by circular dichroism and ultracentrifuge measurements. The results suggest that the peptides assume the form of elongated particles having a significant amount of ordered secondary structure and carrying a dipole parallel to the long axis. Apparently the monomeric peptide molecules undergo, to some extent, a head-to-tail aggregation which is slightly enhanced at lower temperatures. Based on the high-frequency parts of the dielectric dispersion curves the lengths, diameters, and dipole moments of the monomer particles have been determined as 22.5A, 10A, 36 D (P10) and 28.5A, 12A, 64D (P20).
已合成了肽Boc-(L-丙氨酸-氨基异丁酸-L-丙氨酸-氨基异丁酸-L-丙氨酸)n-OMe，其中n = 2（P10）和n = 4（P20），作为抗生素短杆菌肽A的纯疏水模型，已知短杆菌肽A是膜中电压依赖性的成孔剂，在亲脂性介质中显然呈α螺旋结构。在与膜环境相似的溶剂1-辛醇中对这些肽进行了研究。通过介电色散研究可以得出有关分子形状和偶极矩的定量信息。通过圆二色性和超速离心测量获得了有关肽的构象和聚集程度的进一步独立数据。结果表明，这些肽呈现出细长颗粒的形式，具有大量有序的二级结构，并带有与长轴平行的偶极。显然，单体肽分子在一定程度上会发生头对尾聚集，在较低温度下这种聚集会略有增强。根据介电色散曲线的高频部分，已确定单体颗粒的长度、直径和偶极矩分别为22.5埃、10埃、36德拜（P10）和28.5埃、12埃、64德拜（P20）。
