Molle G, Duclohier H, Julien S, Spach G
URA 500 du CNRS, Faculté des Sciences de Rouen, Mont Saint Aignan, France.
Biochim Biophys Acta. 1991 May 7;1064(2):365-9. doi: 10.1016/0005-2736(91)90324-2.
In a previous study, a synthetic analogue of the peptaibol alamethicin, in the sequence of which all alpha-aminoisobutyric acid (Aib) were substituted by leucine residues and the C-terminal residue modified, was shown to display the same single-channel behaviour as alamethicin in planar lipid bilayer, except that the sublevel lifetimes were much reduced. New analogues differing in their C-terminal residue (Phe-NH2, Pheol, Trp-NH2) have now been tested for their single channel properties in neutral lipid bilayers. The conductance amplitudes and open channel lifetimes do not differ significantly from the previous analogue. Thus, the nature of the last residue, which may be located near the membrane interface, does not seem to play an important role in the destabilisation of the conducting aggregate observed after the Aib substitution by Leu. Since the deletion of one residue (Glu18) in the 14-20 moiety induces a slight decrease of the increment between the conductance levels, but has no effect upon the channel lifetimes, this residue and the length of this segment do not interfer much with the channel lifetime of peptaibols. In conclusion the factors influencing the aggregate stability may be sought in the helix-helix interactions.
在之前的一项研究中，一种肽抗生素短杆菌肽A的合成类似物被证明在平面脂质双层中表现出与短杆菌肽A相同的单通道行为，该类似物序列中所有的α-氨基异丁酸（Aib）都被亮氨酸残基取代，且C端残基经过修饰，只是亚水平寿命大幅缩短。现在已经测试了C端残基不同（苯丙氨酸-氨基、苯酚、色氨酸-氨基）的新类似物在中性脂质双层中的单通道特性。其电导幅度和开放通道寿命与之前的类似物没有显著差异。因此，可能位于膜界面附近的最后一个残基的性质，似乎在亮氨酸取代Aib后观察到的导电聚集体的去稳定化过程中并不起重要作用。由于在14 - 20部分缺失一个残基（Glu18）会导致电导水平之间的增量略有下降，但对通道寿命没有影响，所以该残基和这一片段的长度对肽抗生素的通道寿命影响不大。总之，影响聚集体稳定性的因素可能在于螺旋 - 螺旋相互作用。
