Dynamic interactions of cations, water and lipids and influence on membrane fluidity

Rina Kagawa, Yoshinori Hirano, Makoto Taiji, Kenji Yasuoka, Masato Yasui

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)


Cell membranes, which consist of a lipid bilayer, play a critical role in cellular bioactivities. The lipid bilayer interacts dynamically with water as well as ions. Membrane fluidity is lesser in ionic solutions than in pure water, although how ions reduce membrane fluidity has not yet been clarified. Here, we performed 4×100-ns molecular dynamics simulations of a POPE (1-palmitoyl-2-oleoyl-phosphatidyl-ethanolamine [18:1]) lipid bilayer in the presence or absence of ions (NaCl, KCl, or CaCl2) and compared the systems to evaluate the influence of ions on the structural dynamics of membranes. Our simulation revealed that membrane fluidity (no ion-system>Ca-system>K-system>Na-system) did not correspond to the distribution or the direct binding of cations to lipids (Ca2+>Na+>K+). Interestingly, we found that the presence of cations induces dehydration of lipids. The number of cations in the interface region corresponded to the degree of lipid dehydration and the reduction in membrane fluidity (Na+>K+>Ca2+). We therefore propose that membrane fluidity is not affected by direct interactions between cations and lipids, but by the dehydration of lipid molecules in the presence of cations located adjacent to the membrane.

Original languageEnglish
Pages (from-to)130-136
Number of pages7
JournalJournal of Membrane Science
Publication statusPublished - 2013 May 5


  • Dynamic interactions of cations
  • Lipid molecule
  • Molecular dynamics simulation
  • Water and lipids

ASJC Scopus subject areas

  • Biochemistry
  • Materials Science(all)
  • Physical and Theoretical Chemistry
  • Filtration and Separation


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