Lipid bilayers interaction with small molecules

Lipids are building blocks of model and real membranes, which can be combined with proteins and some other important biomolecules to simulate real membranes. The simplest model is hence the self-assembly of only one component of the complex membrane, in this case the lipids. These mono-component lipidic models are often employed in studies as their interaction with small molecules mimics the actual relationship between the cell membrane and a substrate. A commonly employed amphiphatic lipid, dipalmitoyl phosphatidylcholine (DPPC) (Figure 4.6.2), has been widely used to construct these cell membrane motifs, due to its high content in animal cells, and thus its tendency to mimic a valid animal ceU. The supramolecular organization of these (a) DPPC amphiphatic molecules lead to a (b) Langmuir monolayer, (c) bilayer, (d) micelle, and (e) vesicle, which are the available levels of modeling to mimic the cellnlar membrane. 

Pohorille, A., New, M. H., Schweighofer, K. and Wilson, M. A. (1999). Insights from computer simulations into the interactions of small molecules with lipid bilayers. In Membrane Permeability, Vol. 48 100 Years Since Ernest Overton, eds. Deamer, D. W., Kleinzeller, A. and Fambrough, D. M., Academic Press, San Diego pp. 50-76. 

Interaction of small molecules and ions with lipid bilayers is of importance from the point of view of membrane transport and other processes such as aaion of drugs and anesthetics on membranes. This includes a number of antibiotics and fatty acids also. The effect of these perturbations on the lipid bilayer in terms of differences in the structure and dynamics of the lipids close to the perturbative group versus the bulk lipids is also interesting and may... 

The Interaction of Lipid Bilayers with Small Molecules... 

To move through the membrane (change sides or transverse diffusion), a molecule must be able to pass through the hydrophobic portion of the lipid bilayer. For ions and proteins, this means that they must lose their interactions with water (desolvation). Because this is extremely difficult, ions and proteins do not move through membranes by themselves. Small molecules such as C02, NH3 (but not NH ). and water can diffuse through membranes however, most other small molecules pass through the lipid bilayer very slowly, if at all. This permeability barrier means that cells must develop mechanisms to move molecules from one side of the membrane to the other. 

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