Hydration studies on lipid membranes: Classification of water molecules in different bilayers in gel and liquid phase

L. M. ALARCÓN; A. R. VERDE; G. A. APPIGNANESI; M. A. FRÍAS; E. A. DISALVO

Buenos Aires

Workshop; 3rd Workshop ?Structure and Dynamics of Glassy, Supercooled and Nanoconfined Fluids; 2019

UBA, UNS

Weuse molecular dynamics simulations to study the hydration propertiesof lipid membranes, both in the gel state and in the crystallinefluid. We show that while the hydration centers remain significantlyhydrated in both phases, the gel-fluid transition implies significantchanges in the second hydration layer, particularly in the region ofthe hydrocarbon tails. Thus, while the water population is almost nilin the hydrocarbon tails zone in gel state, this region becomespartially accessible to water in crystalline liquid state inmembranes of dipalmitoylphosphatidylcholine (DPPC). In the case ofmembranes composed of unsaturated lipids, the presence of doublebonds modifies the hydration map particularly in the hydrocarbonzone. We also show that the water molecules located in the non-polarzone have a lower hydrogen bond (HB) coordination in comparison withthe molecules of the first hydration layer, which are arranged inrelatively compact ´nanoclusters´. The water molecules in thehydrocarbon tails zone tend to be organized in less compactstructures, like branched chains, with a small population of isolatedmolecules. This behavior is similar to that observed in otherhydration contexts, such as water penetrating carbon nanotubes orhydrophobic pores, reflecting the reluctance of water to sacrifice HBcoordination.p { margin-bottom: 0.08in; direction: ltr; line-height: 100%; text-align: left; }p.western { font-family: "Times New Roman", sans-serif; font-size: 12pt; }p.cjk { font-family: "Droid Sans Fallback"; font-size: 12pt; }p.ctl { font-family: "Lohit Hindi"; font-size: 12pt; }a:link { color: rgb(0, 0, 255); }