Kinetics of the lamellar gel–fluid transition in phosphatidylcholine membranes in the presence of sugars

Abstract

Phase diagrams are presented for dipalmitoylphosphatidylcholine (DPPC) in the presence of sugars (sucrose) over a wide range of relative humidities (RHs). The phase information presented here, determined by small angle X-ray scattering (SAXS), is shown to be consistent with previous results achieved by differential scanning calorimetry (DSC). Both techniques show a significant effect of sucrose concentration on the phase behaviour of this phospholipid bilayer. An experimental investigation into the effect of sugars on the kinetic behaviour of the gel to fluid transition is also presented showing that increasing the sugar content appears to slightly increase the rate at which the transition occurs.

Hydrated/Dehydrated Lipid Phase Transitions Measured Using Nanocalorimetry

“…At times shorter than 100 ms, the phase transition temperature difference between the first two cycles became constant. Our result is in agreement with other observations, which indicates that the water/lipid ratio continuously changes but the transition temperature of DPPC is unchanged for the relatively drystate.…”

Phospholipid Membrane Protection by Sugar Molecules during Dehydration—Insights into Molecular Mechanisms Using Scattering Techniques

“…On modern synchrotron X-ray scattering beam lines [58], we are able to measure the positions of these peaks to good precision on timescales of the order seconds [37,38], as well as using the tunable nature of the X-ray radiation to access different regions of reciprocal/ q -space. This approach allows us to measure the inter-bilayer spacing and the inter-lipid packing in bilayers (Figure 3) using a single instrument configuration for a large number of samples and temperatures, as well as allowing a study of the kinetics of the transitions with or without sugars [38].…”

“…This approach allows us to measure the inter-bilayer spacing and the inter-lipid packing in bilayers (Figure 3) using a single instrument configuration for a large number of samples and temperatures, as well as allowing a study of the kinetics of the transitions with or without sugars [38]. Therefore, many measurements would be impractical using lab-based X-rays sources, and kinetic measurements would be impossible.…”

“…As water is removed at constant temperature, the phospholipids can undergo a transition to the gel phase (Figure 1b), which occurs due to the lipids being compressed in the plane of the membrane, leading to freezing of the lipid tails. We have extensively investigated this transition in single lipid systems in the presence of sugars, controlling the moisture contents by equilibration with various relative humidities [35–38]. Depending on the phospholipid used, other membrane lipid phases may also exist at low hydration.…”

Cold-induced changes affect survival after exposure to vitrification solution during cryopreservation in the south-west Australian Mediterranean climate species Lomandra sonderi (Asparagaceae)

“…occur via osmotic and volumetric effects of the sugars on membranes (Lenné et al 2010). In addition, 137 high intracellular sugar concentrations promote a vitrified state of water during cooling due to the highly 138 viscous nature of their aqueous solutions (Wolfe and Bryant 1999).…”