Abstract
The headgroup conformation of the phospholipid dipalmitoyl-glycero-phosphocholine (DPPC) in monolayers at the air/water interface has been studied by neutron reflection in the fluid like liquid-expanded (LE) and in the crystal like solid (S) phase. Information on the headgroup conformation in the two phases has been obtained by scattering contrast variation of the lipid monolayer using four differently deuterated species of DPPC: perdeuterated, chain perdeuterated, choline group perdeuterated and selectively headgroup deuterated. Since the measurements were done mainly on a subphase of null reflecting water (i.e. water scattering contrast matched to the air) there is no subphase contribution to reflectivity and the simplest one layer model can be employed for the data analysis, thus minimising the number of free parameters. A remarkable change of the headgroup orientation was observed between the LE and the S phase. We found that the phosphate-nitrogen dipole of the DPPC headgroup exhibits an in-plane orientation with respect to the monolayer in the LE phase but it assumes a more parallel orientation to the surface normal at lateral pressures above 30 mN/m (S phase). Moreover, this conformational change is accompanied by a significant alteration of the headgroup hydration.
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Abbreviations
- DPPC:
-
Dipalmitoyl-Phosphatidylcholine
- DMPC:
-
Dimyristoyl-Phosphatidylcholine
- DPPE:
-
Dipalmitoyl-Phosphatidylethanolamine
- DMPE:
-
Dimyristoyl-Phosphatidylethanolamine
- DMPA:
-
Dimyristoyl-Phosphatic Acid
- DMPG:
-
Dimyristoyl-Phosphatidylglycerol
References
Albrecht O, Gruler H, Sackmann E (1978) Polymorphism of lipid monolayers. J Phys (France) 39:301–313
Bayerl TM, Thomas RK, Penfold J, Rennie A, Sackmann E (1990) Specular reflection of neutrons at phospholipid monolayers. Biophys J 57:1095–1098
Bechinger B, Seelig J (1991) Conformational changes of the phosphatidyl headgroup due to membrane dehydration. Chem Phys Lipids 58:1–5
Böhm C, Möhwald H, Leiserowitz L, Als-Nielsen J, Kjaer K (1993) Influence of chirality on the structure of phospholipid monolayers. Biophys J 64:553–559
Büldt G, Gally HU, Seelig A, Seelig J, Zaccai G (1978) Neutron diffraction studies on selectively deuterated phospholipid bilayers. Nature 271:182–184
Fischer A, Sackmann E (1986) Electron microscopy and electron diffraction study of coexisting phases of pure and mixed monolayers transferred onto solid substrates. J Colloid Interface Sci 112:1–14
Helm CA, Möhwald H, Kjaer K, Als-Nielsen J (1987) Phospholipid monolayer density distribution perpendicular to the water surface. A synchrotron X-ray reflectivity study. Europhys Lett 4:697–703
Helm CA, Möhwald H, Kjaer K, Als-Nielsen J (1987) Phospholipid monolayers between fluid and solid states. Biophys J 52:381–390
Helm C, Tippmann-Krayer P, Möhwald H, Als-Nielsen J, Kjaer J (1991) Phases of phosphatidylethanolamine monolayers studied by synchrotron X-ray scattering. Biophys J 60:1457–1476
Jacrot B (1976) Neutron scattering from biological structures. Rep Progr Phys 39:911–953
Johnson SJ, Bayerl TM, Weihan W, Noack H, Penfold J, Thomas RK, Kanellas D, Rennie AR, Sackmann E (1991) Coupling of spectrin and polylysine to phospholipid monolayers studied by specular reflection of neutrons. Biophys J 60:1017–1025
Kjaer K, Als-Nielsen J, Helm CA, Tippmann-Krayer P, Möhwald H (1988) An X-ray scattering study of lipid monolayers at the air-water interface and on solid supports. Thin Solid Films 159:17–28
Knoll W (1981) Volume determination of deuterated dimyristoyl-lecithin by mass and scattering length densitometry. Chem Phys Lipids 28:337–345
König S, Pfeiffer W Bayerl T, Richter D, Sackmann E (1992) Molecular dynamics of lipid bilayers studied by incoherent quasi-elastic neutron scattering. J Phys II France 2:1589–1615
Möhwald H (1990) Phospholipid and phospholipid-protein monolayers at the air water interface. Annu Rev Phys Chem 41:441–476
Nagle JF, Wilkinson AD (1978) Lecithin bilayers. Biophys J 19:159–175
Pascher I, Sundell S, Harlos K, Eibl H (1987) Conformation of packing properties of lipids: The crystal structure of Sodium DMPG. Biochim Biophys Acta 896:77–88
Pearson RH, Pascher I (1979) The molecular structure of lecithin dihydrate. Nature 281:499–501
Penfold J, Thomas RK (1990) The application of specular reflection of neutrons to the study of surfaces and interfaces. J Phys Condens Matter 2:1369–1412
Penfold J, Ward RC, Williams WG (1987) A time of flight neutron reflectometer for surface and interface studies. J Phys E: Sci Instrum 20:1411–1417
Russell TP (1990) X-ray and neutron reflectivity for the investigation of polymers. Mat Sci Rep 5:171–271
Tanford C (1973) The hydrophobic effect: formation of micelles and biological membranes. Wiley, New York
Vakinin D, Kjaer K, Als-Nielsen J, Lösche M (1991) Structural properties of phosphatidylcholine in a monolayer at the air/water interface. Biophys J 59:1325–1332
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Correspondence to: T M. Bayed
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Brumm, T., Naumann, C., Sackmann, E. et al. Conformational changes of the lecithin headgroup in monolayers at the air/water interface. Eur Biophys J 23, 289–295 (1994). https://doi.org/10.1007/BF00213578
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DOI: https://doi.org/10.1007/BF00213578