作者:Masamichi Nishihara、Florent Perret、Toshihide Takeuchi、Shiroh Futaki、Adina N. Lazar、Anthony W. Coleman、Naomi Sakai、Stefan Matile
DOI:10.1039/b501472g
日期:——
The elusive questions how arginine-rich sequences allow peptides and proteins to penetrate cells or to form voltage-gated ion channels are controversial topics of current scientific concern. The possible contributions of exchangeable counterions to these puzzling processes remain underexplored. The objective of this report is to clarify scope and limitations of certain counteranions to modulate cellular uptake and anion carrier activity of oligo/polyarginines. The key finding is that the efficiency of counteranion activators depends significantly on many parameters such as activator–membrane and activator–carrier interactions. This finding is important because it suggests that counteranions can be used to modulate not only efficiency but also selectivity. Specifically, activator efficiencies are found to increase with increasing aromatic surface of the activator, decreasing size of the transported anion, increasing carrier concentration as well as increasing membrane fluidity. Efficiency sequences depend on membrane composition with coronene > pyrene ≫ fullerene > calix[4]arene carboxylates in fluid and crystalline DPPC contrasting to fullerene > calix[4]arene ≈ coronene > pyrene carboxylates in EYPC with or without cholesterol or ergosterol. In HeLa cells, the efficiency of planar activators (pyrene) exceeds that of spherical activators (fullerenes, calixarenes). Polyarginine complexes with pyrene and coronene activators exhibit exceptional excimer emission. Decreasing excimer emission with increasing ionic strength reveals dominant hydrophobic interactions with the most efficient carboxylate activators. Dominance of ion pairing with the inefficient high-affinity sulfate activators is corroborated by the reversed dependence on ionic strength. These findings on activator–carrier and activator–membrane interactions are discussed as supportive of arene-templated guanidinium–carboxylate pairing and interface-directed translocation as possible origins of the superb performance of higher arene carboxylates as activators.
神秘的问题——富含精氨酸的序列如何使多肽和蛋白质穿透细胞或形成电压门控离子通道——是当前科学界争论的话题。可交换配衡离子对这些令人困惑的过程可能的贡献仍未得到充分探索。本报告的目的是澄清某些配衡离子调节寡精氨酸/聚精氨酸细胞摄取和阴离子载体活性的范围和局限性。关键发现是,配衡离子激活剂的效率显著取决于许多参数,如激活剂–膜和激活剂–载体相互作用。这一发现很重要,因为它表明配衡离子不仅可以调节效率,还可以调节选择性。具体而言,随着活化剂芳香表面的增加、转运阴离子尺寸的减小、载体浓度的增加以及膜流动性的增加,活化剂效率提高。效率序列取决于膜组成,在流体和结晶DPPC中,芘环 > 芘 > 富勒烯 > 杯[4]芳烃羧酸盐与在含或不含胆固醇或麦角甾醇的EYPC中富勒烯 > 杯[4]芳烃 ≈ 芘环 > 芘羧酸盐形成对比。在HeLa细胞中,平面型激活剂(芘)的效率超过球型激活剂(富勒烯、杯芳烃)。与芘和芘环激活剂复合的聚精氨酸表现出卓越的激基缔合物发射。随着离子强度的增加,激基缔合物发射减少,揭示了与最高效的羧酸盐激活剂之间占主导地位的疏水相互作用。通过离子强度依赖性的倒置证实了优势离子配对对于效率较低的高亲和硫酸盐激活剂。这些关于激活剂–载体和激活剂–膜相互作用的发现讨论了作为芳烃模板胍基–羧酸配对的支撑,以及作为较高芳烃羧酸作为激活剂的优异性能可能的界面导向转运起源。