Arginine “Magic”: Guanidinium Like-Charge Ion Pairing from Aqueous Salts to Cell Penetrating Peptides

摘要: It is a textbook knowledge that charges of the same polarity repel each other. For two monovalent ions in gas phase at close contact this repulsive interaction amounts to hundreds kilojoules per mole. In aqueous solutions, however, Coulomb repulsion strongly attenuated by factor equal dielectric constant medium. The residual repulsion, which now only units mole, may be principle offset attractive interactions. Probably smallest cationic pair, where combination dispersion and cavitation forces overwhelms consists guanidinium water. Indeed, molecular dynamics with electronic structure calculations electrophoretic, as well spectroscopic, experiments, we have demonstrated cations form (weakly) thermodynamically stable like-charge ion pairs.The importance pairing solutions goes beyond mere physical curiosity...