Fatty acids hydrophobic region, lipid

Liposomes are artificial structures primarily composed of phospholipid bilayers exhibiting amphiphilic properties. Other molecules, such as cholesterol or fatty acids also may be included in the bilayer construction. In complex liposome morphologies, concentric spheres or sheets of lipid bilayers are usually separated by aqueous regions that are sequestered or compartmentalized from the surrounding solution. The phospholipid constituents of liposomes consist of hydrophobic lipid tails connected to a head constructed of various glycerylphosphate... 

Figure 22.3 The basic construction of phosphodiglyceride molecules within lipid bilayers. The fatty acid chains are embedded in the hydrophobic inner region of the membrane, oriented at an angle to the plane of the membrane surface. The hydrophilic head group, including the phosphate portion, points out toward the hydrophilic aqueous environment.

FIGURE 11-3 Fluid mosaic model for membrane structure. The fatty acyl chains in the interior of the membrane form a fluid, hydrophobic region. Integral proteins float in this sea of lipid, held by hydrophobic interactions with their nonpolar amino acid side chains. Both proteins and lipids are free to move laterally in the plane of the... 

Nonhydroxylated and hydroxylated fatty acids (C10-C18) comprise the hydrophobic region of lipid A s. Among these, cyclopropane and, in general, unsaturated fatty acids are lacking. In the following, procedures are described which were applied for the determination of the nature, quantity and binding site of fatty acids present in Salmonella lipid A (39). 

Membranes exhibit a common stmcture, with lipid molecules arranged in the form of one or more bilayers, or lamellae. Since lipids are generally nonfluo-rescent, lipid-bound fluorophores are an excellent tool to study this environment. These membrane probes are poorly soluble in water, and hence they partition readily into the hydrophobic regions of the membranes. The derivatives of anthroyloxy fatty acids (AF), with the fluorophore 9-anthroic acid esterfied to the 2, 6,9, 12, or 16 position along a fatty acid acyl chain (stearic acid or palmitic acid), are frequently used. The stmcture of an AF probe is shown schematically in Fig. 1... 

Lipids are water-insoluble that are either hydrophobic (nonpolar) or amphipathic (polar and nonpolar regions). Lipids are in many ways the most diverse of the biological macromolecules, since they are something of a rag-tag bunch of leftovers. Lipids are pretty much everything in the cell that isn t very water soluble, and chemically they don t have a great deal in common with one another. The best known lipids are probably the fatty acids, so that is where we shall start. 

Many lipids like the fatty acids above have a long non-polar hydrocarbon "tail" region and a small polar "head" region. The hydrocarbon region of the molecule is hydrophobic ( water-hating ), and the polar region is hydrophilic ( water-loving ). 

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