Lipids fatty acid chain length

However, Patton and Carey (42) have suggested that calcium soap formation is a part of usual lipid digestion. Other research indicates that the availability of calcium from calcium soaps infused into rat intestines increases as fatty acid chain length decreases ans as degree of polyunsaturatedness increases (58). 

Fig. 3. Structures of selected polymerizable phosphatidylcholine (PC) lipids. The fatty acid chain lengths may vary from 12 to over 20 atoms.

Ohshima, T., Ratnayake, W.M.N., and Ackman, R.G. 1987. Cod lipids, solvent systems and the effect of fatty acid chain length and unsaturation on lipid class analysis by Iatroscan TLC-FID. J. Am. Oil Chem. Soc. 64 219-223. 

The phase behavior of a synthetic lecithin, dipalmitoyllecithin, as analyzed by Chapman and co-workers (5), is diagrammed in Figure 3. The main features are the same as in the phase diagram of egg lecithin a mixture of numerous homologs. As a consequence of the variation in fatty acid chain length, the chain melting point is lowered which means that the critical temperature for formation of liquid crystalline phases is reduced. This temperature is about 42 °C for dipalmitoyllecithin, and, if the lamellar liquid crystal is cooled below this temperature, a so-called gel phase is formed. The hydrocarbon chains in the lipid bilayers of this phase are extended, and they can be regarded as crystalline. The gel phase and the transitions between ordered and disordered chains are considered separately. 

In general, the migration order of any lipid class is determined by the overall number of double bonds in the molecule. Thus the retention of common fatty acids (chain lengths of 16-22 carbon atoms, methylene interrupted double bonds) increases with increasing number of double... 

One issue that complicates efforts to develop a model for the mechanism by which peptide ion channels work is the width of the bilayer that must be spanned by the transmembrane helix. Vodyanoy and Hall (251) measured the dielectric thickness of monoglyceride bilayers and found it to vary from 3.1 to 2.0 nm as the fatty acid chain length went from C22 to C14. The crystal structure (252) of the photosynthetic reaction center indicates a 3.0-3.1-nm hydrophobic zone perpendicular to the membrane that is smaller than might be expected for C18 lipids but is in accord with estimates of dielectric thickness as well as recent physical studies (253). With the assumption that a transmembrane segment must span this thickness to give a stable pore structure, a rise per residue of 1.5 A can be estimated for an a-helix, and 20 amino acid residues would be required. Peptides shorter than 20 residues, such as mastoparan and emerimicin, are capable of ion channel formation,... 

Christophe, A., Verdonk, G., Mashali, M., and Sandra, P. (1982) Fatty Acid Chain Length Combinations in Ascitic Fluid Triglycerides Containing Lymphatic Absorbed Medium Chain Fatty Acids, Lipids 17,759-761. 

The permeability of liposomes prepared from synthetic lecithin have provided useful data which help to explain functional changes in membranes in terms of an alteration in bilayer structure. For example, the rate of water permeation through liposomes decreases 10-fold, and the of permeation increases from about 9 to 26 kcal mol" below the transition temperature for the lipids (Block et al., 1975). Rates of permeation for electrolytes and nonelectrolytes were found to be maximum at, or near, the temperature of the transition where fluid- and solid-phase lipids coexist, and decreased in both the gel and fluid phases below and above this temperature (Block et al., 1976). Since the order-disorder transition of lipids is accompanied by a decrease in the area per molecule, it was postulated that pores developed in the bilayer at the transition temperature and that the number and lifetime of these pores was dependent upon the fatty acid chain length of the lipids (Block eta/., 1976). 

Both 2- and 3-D assemblies of lipid A-mono or diphosphate constructed from single or multiple chemical entities of known chemical composition ( coded subunits ) were quite complex. These assemblies were very unlikely to be loose or unordered combinations of lipid A molecules or of their analogs. The coded subunit addresses the chemical appearances of single or identical chemical stractures of lipid A-phosphate. However, they were non-identical and differed in chemical structure for example number of chiral fatty acid chains, length of the hydrocarbon chain (number of carbons), inserted double bonds in the hydrocarbon chain, and hexose compositions (Christ et al., 2003). The assemblies were characterized by being comprised of two phosphates residues one at the reducing end and the other one at the non-reducing end for the... 

Several precedents exist for the intracellular sorting of lipids to different membranes according to fatty acid chain length [51, 52],... 

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