Arginine magic with new counterions up the sleeve

作者：Nishihara M; Perret F; Takeuchi T; Futaki S; Lazar AN; Coleman AW; Sakai N^*; Matile S

来源：Organic and Biomolecular Chemistry, 2005, 3(9): 1659-1669.

DOI：10.1093/b501472g

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 an. 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 panar 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.

• 出版日期2005