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首页> 外文期刊>Biochimica et biophysica acta. Biomembranes >Stabilization of O-pyromellitylgramicidin channels in bilayer lipid membranes through electrostatic interaction with polylysines of different chain lengths
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Stabilization of O-pyromellitylgramicidin channels in bilayer lipid membranes through electrostatic interaction with polylysines of different chain lengths

机译：通过与不同链长的聚赖氨酸发生静电相互作用，稳定双层脂质膜中的O-邻苯三酚-格拉西米丁通道

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Functioning of membrane proteins, in particular ionic channels, can be modulated by alteration of their arrangement in membranes. We addressed this issue by studying the effect of different chain length polylysines on the kinetics of ionic channels formed in a bilayer lipid membrane (BLM) by O-pyromellitylgramicidin carrying three negative charges at the C-terminus. The method of sensitized photoinactivation was applied to the analysis of the channel association-dissociation kinetics (characterized by the exponential factor of the curve describing the time course of the flash-induced decrease in the transmembrane current, τ). Addition of polylysine to the bathing solutions of BLM led to the deceleration of the photoinactivation kinetics, i.e. to the increase in τ. It was shown here that for a series of polylysines differing in their chain lengths, the value of τ grew as their concentration increased above a threshold level until at a certain concentration of each polylysine τ reached maximum. At higher polylysine concentrations τ began to decrease and finally became close to the control level observed in the absence of polylysine. With lengthening of the polylysine chain the maximum value of τ increased, the concentration dependence became steeper, and the threshold concentration decreased. The increase in the ionic strength of the medium shifted the concentration dependence of τ to higher polylysine concentrations and decreased the maximum value of τ. It was concluded that the increase in τ was caused by the formation of domains of O-pyromellitylgramicidin molecules induced by binding of polylysines. This can be related to functional aspects of polycationinduced sequestering of negatively charged transmembrane peptides in neutral membranes.
机译：膜蛋白的功能，特别是离子通道，可以通过改变其在膜中的排列来调节。我们通过研究不同链长的多赖氨酸对在C末端带有三个负电荷的O-pyromellitylgramicidin在双层脂质膜（BLM）中形成的离子通道动力学的影响来解决此问题。敏化的光灭活方法被用于分析通道缔合-解离动力学（以曲线的指数因子为特征，该因子描述了闪变引起的跨膜电流τ减小的时间过程）。在BLM的沐浴溶液中添加聚赖氨酸会导致光灭活动力学的降低，即τ的增加。在此表明，对于一系列链长不同的聚赖氨酸，τ的值随着其浓度增加到阈值水平以上而增长，直到每个聚赖氨酸的特定浓度τ达到最大值。在较高的多聚赖氨酸浓度下，τ开始下降，最终变得接近在不存在多聚赖氨酸的情况下所观察到的对照水平。随着聚赖氨酸链的延长，τ的最大值增加，浓度依赖性变陡，阈值浓度降低。介质离子强度的增加将τ的浓度依赖性转移到更高的聚赖氨酸浓度，并降低了τ的最大值。可以得出结论，τ的增加是由聚赖氨酸结合引起的O-pyromellitylgramicidin分子域的形成引起的。这可能与聚阳离子诱导的隔离中性膜中带负电的跨膜肽的功能方面有关。

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