| Ions are prevalent in both the cytosol and exterior of a bio-membrane. Ions directly interact with membrane lipids and thus influence membrane fusion, membrane protein binding as well as signal transduction across membranes. Numerous Molecular dynamics (MD) simulations have been performed to probe the effects of ions on the structures and dynamics of lipid bilayers composed of a single phospholipid. Lipid rafts, important functional microdomains in membranes, are asymmetric bilayers which have been involved in many physiological process. However, little is known about the effects of ions on lipid rafts. Here, we reveal the effects of Na+ã€K+ã€Ca2+ã€Mg2+ on lipid rafts by performing MD simulations.In Chapter 2, we constructed two raft-like bilayers (SC bilayer and PPC bilayer), and carried out microsecond MD simulations to study the interactions between Na+ã€K+ and two raft-lipid bilayers. It has been revealed that the structures of the SC bilayer is quite different from the PPC bilayer, and Na+, K+show weak binding affinity to both raft-like bilayers. In Chapter 3, we further study the effects of Na+, K+, Ca2+, Mg2+ on the structure and dynamic properties of lipid raft-like bilayers. It is found that Ca2+ shows the strongest ability to both SC bilayer and PPC bilayer. On the contrary, none of the Mg2+ binds to membrane surface. In addition, the effects of the Ca2+on the SC bilayer and PPC bilayer are opposite. These different impacts of Ca on the SC bilayer and PPC bilayer can further adjust the functions of lipid rafts.Besides, Zn2+ has important physiological functions in the neurotransmitter system, but there is a lack of understanding on the interaction between Zn2+and lipid bilayers. In Chapter 4, another molecular dynamic simulations are carried out on interactions between Na+, Ca2+, Zn2+ and POPC bilayer. It has been revealed that the binding efficiency of these cations with POPC lipids is in the following order:Ca2+> Zn2+> Na+. |
PDF Full Text Request