Pressure effects on the structure of lyotropic lipid mesophases and model biomembrane systems

Abstract

Lipid systems, which provide valuable model systems for biological membranes, display a variety of polymorphic phases, depending on their molecular structure and environmental conditions. By use of X-ray and neutron diffraction the temperature-and pressure-dependent structure and phase behavior of lipid systems, differing in chain configuration and headgroup structure, have been studied. Besides lamellar phases also nonlamellar phases have been investigated. Hydrostatic pressure has been used as a physical parameter for studying the stability and energetics of lyotropic lipid mesophases, but also because high pressure is an important feature of certain natural membrane environments (e.g., marine biotopes) and because the high pressure phase behavior of biomolecules is of biotechnological interest (e.g., high pressure food processing). We demonstrate that temperature and pressure have noncongruent effects on the structural and phase behavior. By using the pressure-jump relaxation technique in combination with time-resolved synchrotron X-ray diffraction, the kinetics of different lipid phase transformations was also investigated. The time constants for completion of the transitions depend on the direction of the transition, the symmetry and topology of the structures involved, and also on the pressure-jump amplitude. In addition, the effect of incorporating ions, steroids and polypeptides into bilayers on the temperature-and pressure-dependent phase behavior of the lipid systems is discussed.

Characterization of High-Hydrostatic-Pressure Effects on Fresh Produce Using Chlorophyll Fluorescence Image Analysis

“…Lower treatment temperatures increased the initial permeabilization of the cellular membranes. This was attributed to the influence of a solidification of the membrane since model membranes and membranes in bacteria showed a phase transition from the liquid crystalline to the gel phase at low temperatures and elevated pressures (Winter and Czelik 2000). This solidification facilitates damaging of the membranes, caused by different compressibility of cell inclusions like starch granules or gas vacuoles.…”

High pressure–low temperature processing of foods: impact on cell membranes, texture, color and visual appearance of potato tissue

“…Lower treatment temperatures increased the initial permeabilization of the cellular membranes. This was attributed to the influence of a solidification of the membrane, since model membranes and membranes in bacteria showed a phase transition from the liquid-crystalline to the gel phase at low temperatures and elevated pressures (Ulmer et al, 2002;Winter & Czeslik, 2000). This solidification facilitates damaging of the membranes caused by different compressibility of cell inclusions like starch granules or gas vacuoles.…”

“…Model membranes (Winter & Czeslik, 2000) and the cellular membranes of bacteria (Ulmer, Herberhold, Fahsel, Gaenzle, Winter & Vogel, 2002) are proven to be subjected to a phase transition from the liquid-crystalline phase to a more rigid gel phase, when they are treated with high pressure or low temperature processes. In bacteria, the inactivation of membrane-bound enzymes is attributed to cell death (Ulmer et al, 2002;Wouters, Glaasker, & Smelt, 1998).…”

High pressure cell for neutron reflectivity measurements up to 2500 bar

“…They exhibit a rich structural polymorphism, depending on the lipid molecular structure and the environmental conditions, such as the water content, ionic strength, temperature, and pressure. 15,16 One example is lamellar phospholipid structures, which provide the basic structural element of biological membranes. In the lamellar structure, the interfaces are flat and often periodically stacked.…”

“…de. have also been employed to investigate proteins and lipids under high pressure conditions up to several kbar. [10][11][12][13][14][15][16][17][18][19] SAXS and SANS can be used to probe overall molecular structures and aggregation processes in solution. However, in recent years, biochemical interfacial structures and biomolecular interactions at interfaces, such as lipid membranes, have received increased interest.…”