In this work, the
influence of membrane curvature on the Ca2+binding to
phospholipid bilayers is investigated by means
of molecular dynamics simulations. In particular, we compared Ca2+binding to flat, elastically buckled, or uniformly bent
zwitterionic and anionic phospholipid bilayers. We demonstrate that
Ca2+ions bind preferably to the concave membrane surfaces
in both types of bilayers. We also show that the membrane curvature
leads to pronounced changes in Ca2+binding including differences
in free ion concentrations, lipid coordination distributions, and
the patterns of ion binding to different chemical groups of lipids.
Moreover, these effects differ substantially for the concave and convex
membrane monolayers. Comparison between force fields with either full
or scaled charges indicates that charge scaling results in reduction
of the Ca2+binding to curved phosphatidylserine bilayers,
while for phosphatidylcholine membranes, calcium binds only weakly
for both force fields.