J. Phys. Chem. B 2010, 114, 13249–13254
13249
Ca2+ Bridging of Apposed Phospholipid Bilayers Zeena K. Issa,† Charles W. Manke,† Bhanu P. Jena,†,‡ and Jeffrey J. Potoff*,† Department of Chemical Engineering and Materials Science, Wayne State UniVersity, Detroit, Michigan 48202, Department of Physiology, School of Medicine, Wayne State UniVersity, Detroit, Michigan 48202 ReceiVed: June 22, 2010; ReVised Manuscript ReceiVed: July 30, 2010
In an effort to provide insight into the mechanism of Ca2+-induced fusion of lipid vesicles, molecular dynamics simulations in the isobaric-isothermal ensemble are used to investigate interactions of Ca2+ with apposed lipid bilayers in close proximity. Simulations reveal the formation of a Ca2+-phospholipid “anhydrous complex” between apposed bilayers, whereas similar calculations performed with Na+ display only complexation between neighboring lipids within the same bilayer. The binding of Ca2+ to apposed phospholipids brings large regions of the bilayers into close contact (
