Pretransition-ripples in bilayers of dipalmitoylphosphatidylcholine: undulation or periodic segments? A freeze-fracture study

Meyer, H.

doi:10.1016/0005-2760(96)00054-9

Cited by 31 publications

(26 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…chain tilt) over such relatively large periodical distances. The periodic change in tilt direction of normal ripples is also an unresolved question (Meyer 1996).…”

Section: Discussionmentioning

confidence: 99%

The effect of sterols on structures formed in the gel/subgel phase state of dipalmitoylphosphatidylcholine bilayers

Meyer¹,

Semmler²,

Quinn³

1997

Molecular Membrane Biology

View full text Add to dashboard Cite

The effect of cholesterol and lanosterol on the formation of structures in the gel/subgel phase of 1,2-dipalmitoylphosphatidylcholine was investigated using freeze-fracture electron microscopy and X-ray diffraction. Mixtures with up to 25 mol% sterol were analysed after annealing for between several days and some months at 4 degrees C. Bilayers of DPPC with 5 or 10 mol% sterol showed a domain structure in the gel state. There are rounded or lens-like and often inclined plates within less smooth either plane or striped bilayer areas. The stripes are formed by parallel lines separated by a distance of 30-60 nm. Parallel lines can be induced also in the less smooth but plane areas by warming up to 25 degrees C. X-ray diffraction showed two lamellar repeat spacings at 6.45 and 8.3 nm in both 5 and 10 mol% samples. The plates are interpreted as domains of (nearly) pure DPPC within the sterol containing bilayer. Stripes are present if the concentration of cholesterol is below a critical value (approx. 15 mol%). With time of incubation at 4 degrees C curved deformations appear in parts of the bilayers. Two main types are formed. The small type has a repeat distance of about 100 nm and the large type of about 400 nm. The curved deformations were progressively flattened by warming up to 25-32 degrees C with an accompanying reappearance of stripes but no plates. After prolonged annealing at 4 degrees C there is also the formation of regular ripples. It is concluded that in presence of 5 and 10 mol% sterol in bilayers of 1,2-dipalmitoy-phosphatidylcholine the immiscibility of gel phase and subgel phase changes during prolonged annealing at 4 degrees C. We assume a rearrangement of the molecules into a homogeneous phase state with liquid-ordered properties.

show abstract

“…chain tilt) over such relatively large periodical distances. The periodic change in tilt direction of normal ripples is also an unresolved question (Meyer 1996).…”

Section: Discussionmentioning

confidence: 99%

The effect of sterols on structures formed in the gel/subgel phase state of dipalmitoylphosphatidylcholine bilayers

Meyer¹,

Semmler²,

Quinn³

1997

Molecular Membrane Biology

View full text Add to dashboard Cite

show abstract

“…Multilayers display a pretransition, which is clearly distinguishable from the main chain-melting transition. The pretransition, however, can also be found in unilamellar systems (Lichtenberg et al, 1984;Meyer, 1996) where it is broader and less separated from the main transition (Heimburg, 1998). In unilamellar systems, the heat capacity in between the two transitions is found to be above the baseline level.…”

Section: Introductionmentioning

confidence: 95%

“…Spectral changes in the pretransition can be seen in fluorescence data (Binder and Dittes, 1987;Epps et al, 1997;Krasnowska et al, 1998), ESR (Tsuchida and Hatta, 1988;Heimburg et al, 1992), and infrared experiments (Le Bihan and Pezolet, 1998). In freeze fracture electron microscopy and atomic force microscopy, the ripples can be directly visualized (Sackmann, 1995;Czajkowsky et al, 1995;Meyer, 1996;Meyer et al, 1996).…”

Section: Introductionmentioning

confidence: 99%

A Model for the Lipid Pretransition: Coupling of Ripple Formation with the Chain-Melting Transition

Heimburg

2000

Biophysical Journal

244

225

View full text Add to dashboard Cite

Below the thermotropic chain-melting transition, lipid membrane c(P) traces display a transition of low enthalpy called the lipid pretransition. It is linked to the formation of periodic membrane ripples. In the literature, these two transitions are usually regarded as independent events. Here, we present a model that is based on the assumption that both pretransition and main transition are caused by the same physical effect, namely chain melting. The splitting of the melting process into two peaks is found to be a consequence of the coupling of structural changes and chain-melting events. On the basis of this concept, we performed Monte Carlo simulations using two coupled monolayer lattices. In this calculation, ripples are considered to be one-dimensional defects of fluid lipid molecules. Because lipids change their area by approximately 24% upon melting, line defects are the only ones that are topologically possible in a triangular lattice. The formation of a fluid line defect on one monolayer leads to a local bending of the membrane. Geometric constraints result in the formation of periodic patterns of gel and fluid domains. This model, for the first time, is able to predict heat capacity profiles, which are comparable to the experimental c(P) traces that we obtained using calorimetry. The basic assumptions are in agreement with a large number of experimental observations.

show abstract

“…DPPC) are used a corrugated bilayer is formed in the temperature range between pretransition and main transition. Beside electron microscopy involving cryofixation (Krbecek et al, 1979;Erk et al, 1996;Meyer, 1996) this ripple phase has been observed with other methods where no freezing is required, for example with atomic force microscopy (Mou et al, 1994;Czajkowsky et al, 1995) and X-ray scattering (Tardieu et al, 1973;Wack & Webb, 1989;Yao et al, 1991;Rappolt & Rapp, 1996;Sun et al, 1996).…”

Section: High-pressure-induced Modifications Of Phospholipid Membranementioning

confidence: 99%

“…Membranes consisting of phospholipids with a phosphocholine headgroup and saturated acyl chains form a characteristic rippled superstructure in a temperature range below the main transition where the lipid chains melt. These ripples characterize the P β′ ‐phase in the gel state ( Tardieu et al ., 1973 ; Zasadzinski et al ., 1988 ; Meyer, 1996) and we used the characteristic morphology of the ripple‐phase to study the influence of high pressure. The high water content used (> 95% wt/wt) resulted in the formation of multilamellar vesicles (liposomes).…”

Section: Introductionmentioning

confidence: 99%

High‐pressure freezing causes structural alterations in phospholipid model membranes

Semmler

Wunderlich

Richter

et al. 1998

Journal of Microscopy

View full text Add to dashboard Cite

The influence of high-pressure freezing (HPF) on the lipid arrangement in phospholipid model membranes has been investigated. Liposomes consisting of pure dipalmitoyl-phosphatidylcholine (DPPC) and of DPPC mixed with a branched-chain phosphocholine (1,2-di(4-dodecyl-palmitoyl)- sn-glycero-3-phosphocholine) have been analysed by freeze-fracture electron microscopy. The liposomes were frozen either by plunging into liquid propane or by HPF. The characteristic macroripple-phase of the two-component liposome system is drastically changed in its morphology when frozen under high-pressure conditions. The influence of ethanol which acts as pressure transfer medium was ruled out by control experiments. In contrast, no high-pressure alterations of the pure DPPC bilayer membrane have been observed. We assume that the modification of the binary system is due to a pressure-induced relaxation of a stressed and unstable lipid molecule packing configuration. HPF was performed with a newly designed sample holder, for using sandwiched copper platelets with the high-pressure freezing machine Balzers HPM010. The sandwich construction turned out to be superior to the original holder system with regard to freeze-fracturing of fluid samples. By inserting a spacer between the supports samples with a thickness of 20-100 microns can be high-pressure frozen. The sandwich holder is provided with a thermocouple to monitor cooling rates and allows exact sample temperature control. Despite a two-fold mass reduction compared to the original holder no HPF cooling rate improvement has been achieved (4000 degrees Cs-1). We conclude that the cooling process in high-pressure freezing is determined mainly by cryogen velocity.

show abstract

Pretransition-ripples in bilayers of dipalmitoylphosphatidylcholine: undulation or periodic segments? A freeze-fracture study

Cited by 31 publications

References 27 publications

The effect of sterols on structures formed in the gel/subgel phase state of dipalmitoylphosphatidylcholine bilayers

The effect of sterols on structures formed in the gel/subgel phase state of dipalmitoylphosphatidylcholine bilayers

A Model for the Lipid Pretransition: Coupling of Ripple Formation with the Chain-Melting Transition

High‐pressure freezing causes structural alterations in phospholipid model membranes

Contact Info

Product

Resources

About