Molecular Dynamics Simulations of the Interactions of DMSO with DPPC and DOPC Phospholipid Membranes

Molecular dynamics simulations have been used to investigate
the
effect of DMSO on 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine
(DPPC) and 1,2-dioleoyl-sn-glycero-3-phosphocholine
(DOPC) phospholipid bilayers. The concentration of DMSO was varied
between 0 and 25.0 mol %. For both lipids, DMSO causes the membrane
to expand in the plane of
the membrane while thinning normal to that plane. Above a critical
concentration, pores in the membrane form spontaneously, and if the
concentration is increased further, then the bilayer structure is
destroyed. Even at concentrations below those required to induce pores,
DMSO readily diffuses across the bilayers. The free-energy profile
associated with the diffusion of a DMSO molecules across the membrane
has been calculated. The simulations suggest that the DOPC bilayer
is more resistant to the deleterious effects of DMSO, both increasing
the stability of the membranes and decreasing the rate at which DMSO
diffuses across the membrane. In this way, the work highlights the
importance of investigating the lipid composition of cell membranes
when characterizing the effects of cryosolvents.