We examined the effect of membrane surface charge density, temperature, and salt concentration on the structure of multilamellar phases, by mixing the negatively charged saturated lipid 1,2-dilauroyl-sn-glycero-3-phospho-L-serine (DLPS) with its zwitterionic (dipolar, net neutral) lipid analogue, 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC). In another set of experiments, we mixed the negatively charged unsaturated lipid dioleoyl(C18:1)-sn-glycero-3-phospho-L-serine (DOPS) with its zwitterionic lipid analogue 1,2- dioleoyl(C18:1)-sn-glycero-3-phosphocholine (DOPC) and investigated the effect of membrane surface charge density as well as salt concentration and type.  We determined the critical conditions for tight coupling between like-charged membranes and characterized the structural changes of those phases as a function of membrane charge density and temperature (read more).