Lipids membrane models

In the first step, lipid model membranes have been generated (Fig. 15) on the air/liquid interface, on a glass micropipette (see Section VIII.A.1), and on an aperture that separates two cells filled with subphase (see Section VIII.A.2). Further, amphiphilic lipid molecules have been self-assembled in an aqueous medium surrounding unilamellar vesicles (see Section VIII.A.3). Subsequently, the S-layer protein of B. coagulans E38/vl, B. stearother-mophilus PV72/p2, or B. sphaericus CCM 2177 have been injected into the aqueous subphase (Fig. 15). As on solid supports, crystal growth of S-layer lattices on planar or vesicular lipid films is initiated simultaneously at many randomly distributed nucleation... 

Ion Binding and Water Orientation in Lipid Model Membrane Systems Studied by NMR... 

L. K. Tamm and I. Bartoldus, Antibody-binding to lipid model membranes - the large-ligand effect, Biochemistry 27, 7453-7458 (1988). 

Burger, K. N., Nieva, J. L., Alonso, A., and Verkleij, A. J. (1991), Phospholipase C activity-induced fusion of pure lipid model membranes. A freeze fracture study, Biochim. Biophys. Acta, 1068,249-253. 

Biological Background Lipid Mesomorphic Phase Behavior Differential Scanning Calorimetry DSC Studies of Lipid Model Membranes DSC Studies of Biological Membranes... 

Mention should be made here of the recently developed technique of pressure perturbation calorimetry (PPC), which measures the temperature-dependent volume change of a solute or colloidal particle in aqueous solution. PPC can also be used to detect thermotropic phase transitions in lipid model membranes and to characterize the accompanying volume changes and the kinetics of the phase transition. PPC essentially measures the heat change that results from small pressure changes at a constant temperature in a high-sensitivity isothermal calorimeter. For an excellent recent review on PPC as applied to lipid systems, the reader is referred to Heerklotz (19). 

Trauble H, Sackmann E. Studies of crystalline-liquid crystalline phase-transihon of lipid model membranes.3. Structure of a steroid-lecithin system below and above lipid-phase transition. J. Am. Chem. Soc. 1972 94 4499-4510. 

Kinsky, S.C. Antibody-complement interaction with lipid model membranes. Biochim. Biophys. Acta. 1972, 265, 1-23. 

Seto, G. W., Marwaha, S., Kobewka, D. M., et al. (2007) Interactions of the Australian tree frog antimicrobial peptides aurein 1.2, citropin 1.1 and maculatin 1.1 with lipid model membranes Differential scanning calorimetric and Fourier transform infrared spectroscopic studies. Biochimica et Biophysica Acta, 1768, 2787-2800. 

Bermejo, J., Barbadillo, A., Tato, F., and Chapman, D. (1975). FEBS Lett. 52, 69. Magnetic Resonance Studies on the Interaction of Antidepressants with Lipid Model Membranes. 

In order to elucidate the physicochemical properties of such a biological membrane interface, several model membrane systems (lipid monolayer, lipid bilayers, and protein-incorporated lipid model membrane systems) which mimic biological membrane interfaces have also been studied.In particular, many properties at the membrane surface are intimately related to the electrical potential originating from the fixed charge or electrical polarization of the membrane constitutents. 

Still, the problem of isolation, identification of the chemical structure, and reconstitution of channels on the basis of lipid model membranes remains the most urgent one. Therefore, investigations of the electrochemical properties of lipid bilayers and of their interaction and fusion with lipid vesicles gain particular importance, especially since there are no apparent alternative ways of introduction of hydrophobic proteins into fiat membranes. 

Amado, E. and Kressler, J. 2011. Interactions of amphiphihc block copolymers with lipid model membranes. Current Opinion in Colloid and Interface Science 16(6) 491 98. 

Alving BM, Hojima Y, Pisano JJ, Mason BL, Buckingham RE, Mozen MM, Finlayson JS (1978) Hypotension associated with prekallikrein activator (Hageman-factor fragments) in plasma protein fraction. N Engl J Med 299 66-70 Alving CR (1977) Immune reactions of lipids and lipid model membranes. In The antigens, vol 4. Academic Press, New York, pp 3-72... 

In this contribution, there will be described the principal type of calorimetric experiments which can be perfonned to elucidate the behavior of lipid model membranes. Most of the examples come from work performed in the author s laboratory. Numerous other groups are involved with calorimetric studies on tliese model membrane systems and there exists a vast amount of literature, because calorimetry has become a standard analytical method in the last ten to twenty years. It is our goal to present the principles of the method and not an extensive review over the current literature. Therefore, this chapter is necessarily biased towards work from the author s laboratory and apologies are extended to all those whose work is not adequately represented here. 

---