title: Guanidinium Pairing Facilitates Membrane Translocation.
abstract: Ab initio free energy calculations of guanidinium pairing in aqueous solution confirm the counterintuitive conjecture that the like-charge ion pair is thermodynamically stable. Transferring the guanidinium pair to the inside of a POPC lipid bilayer, like-charge ion pairing is found to occur also inside the membrane defect. It is found to contribute to the nonadditivity of ion transfer, thereby facilitating the presence of ions inside the bilayer. The effect is quantified by free energy decomposition and comparison with ammonium ions, which do not form a stable pair. The presence of two charges inside the center of the bilayer leads to the formation of a pore. Potential consequences for cell penetrating peptides and ion conduction are drawn.
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences , Flemingovo nám. 2, CZ-166 10 Prague 6, Czech Republic.|Institut für Physikalische and Theoretische Chemie, Universität Regensburg , 93040 Regensburg, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Allolio
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences , Flemingovo nám. 2, CZ-166 10 Prague 6, Czech Republic.
authors.forename: Katarina
authors.initials: K
authors.lastname: Baxova
authors.affiliation: Institut Rudjer Bošković, Bijenička cesta 54, 10000 Zagreb, Croatia.
authors.forename: Mario
authors.initials: M
authors.lastname: Vazdar
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences , Flemingovo nám. 2, CZ-166 10 Prague 6, Czech Republic.|Department of Physics, Tampere University of Technology , P.O. Box 692, FI-33101 Tampere, Finland.
authors.forename: Pavel
authors.initials: P
authors.lastname: Jungwirth
mesh_terms: D019791:Guanidine / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry*; D056004:Molecular Dynamics Simulation; D010713:Phosphatidylcholines / Q000737:chemistry*; D011789:Quantum Theory; D013816:Thermodynamics; D014867:Water / Q000737:chemistry
chemical_list: D008051:Lipid Bilayers; D010713:Phosphatidylcholines; D014867:Water; D019791:Guanidine; C028694:1-palmitoyl-2-oleoylphosphatidylcholine