Fatty acid moieties

The lipid content of the membranes can be varied, allowing systematic examination of the effects of varying lipid composition on certain functions. For instance, vesicles can be made that are composed solely of phosphatidylchohne or, alternatively, of known mixtures of different phospholipids, glycohpids, and cholesterol. The fatty acid moieties of the lipids used can also be varied by employing synthetic lipids of known... 

Phosphatidylcholine, commonly known as lecithin, is the most commonly occurring in natnre and consists of two fatty add moieties in each molecule. Phosphati-dylethanolamine, also known as cephahn, consists of an amine gronp that can be methylated to form other compounds. This is also one of the abundant phospholipids of animal, plant, and microbial origin. Phosphatidylserine, which has weakly acidic properties and is found in the brain tissues of mammals, is found in small amounts in microorganisms. Recent health claims indicate that phosphatidylserine can be used as a brain food for early Alzheimer s disease patients and for patients with cognitive dysfunctions. Lysophospholipids consist of only one fatty acid moiety attached either to sn-1 or sn-2 position in each molecule, and some of them are quite soluble in water. Lysophosphatidylchohne, lysophosphatidylserine, and lysophos-phatidylethanolamine are found in animal tissues in trace amounts, and they are mainly hydrolytic products of phospholipids. 

O. Geiger, E. P. Kennedy, V. N. Reinhold, and B. J. J. Lugtenberg, A novel, highly unsaturated fatty acid moiety of lipooligosaccharide signals determines host specificity of Rhizohium. Nature 354 125 (1991). 

The poly(3HO) depolymerase differs from poly(HASCL) depolymerases in several of its biochemical properties it is specific for poly(HAMCL) and for artificial esters such as p-nitrophenylacyl esters with six or more carbon atoms in the fatty acid moiety. Poly(3HB) and other poly(HASCL) are not hydrolyzed. The enzyme is not inhibited by dithioerythritol or by EDTA and therefore apparently does not contain essential disulfide bonds. It is also not dependent on Ca2+ or other divalent cations. 

Wax esters have similar relative molecular masses to diacylglycerols and are eluted under comparable gas chromatographic conditions. Alternatively, the alcohol and fatty acid moieties can be released by saponification and their methyl esters subjected to gas chromatography. 

Studies of the reaction of ozone with simplified lipid systems have shown that malonaldehyde can be produced by direct ozonolysis. The use of malonaldehyde assay as an index of lipid peroxidation is therefore invalid in ozone studies. Liposomes formed from egg lecithin and prepared in aqueous media were quite resistant to ozone, but the contribution of polyconcentric spheres to this resistance has not been fully assessed. However, the bilayer configuration, with the susceptible unsaturated fatty acids shielded from ozone by the hydrophilic areas of the molecule, may be resistant. In hexane, where the fatty acid moieties are exposed, ozone reacts stoichiometrically with the double bonds. The experiments with aqueous suspensions of phosphatidylcholine gave no evidence of the formation of lipid peroxides,nor did experiments with films of fatty acids exposed to ozone. ... 

Nordstrom (19) demonstrated that esters are formed primarily by a direct biosynthetic process during fermentation in which acyl-CoA compounds containing the particular fatty acid moiety combine with alcohols of the medium, which explains the predominance of ethyl esters. Ester formation during fermentation does not appear to be direct esterification between alcohols and free fattty acids. However, some direct esterification may occur on the plates of a distilling column where acids and alcohols are most concentrated. 

Marine lipids with their diversity of unsaturated and branched chain acid moieties are a difficult class of materials to analyze. Ruminants (sheep, goats, cows, etc.) have a bacterial "factory" in the rumen which is able to produce branched-chain partially-hydrogenated lipids from ingested plant lipids. These lipids are incorporated into the milk and meat of the animals and eventually into animals which feed upon the ruminants. As a rule animal lipids are highly complex in comparison to plant materials. Although the branched chain materials are usually present in low concentration when compared to the common fatty acid moieties, complete description of these fats requires more sophisticated GC and thus long open tubular columns in tandem with mass spectrometry and computer analysis of the data has become an important approach. Even with a 100-m column, subcutaneous lipids of barley-fed lambs were so complex that prior fractionation with urea adducts was necessary (17). 

As noted earlier, natural alcohols are produced from coconut oil and tallow as well as some other fats and oils—palm kernel oil, palm oil, sperm whale oil, etc. Most of these natural oils actually consist of fatty triglycerides, i.e., glycerol esterified by three molecules of fatty acid. There is very little free alcohol present in these materials, and the alcohols are derived from the fatty acid moiety of the triglyceride by reduction. 

Other methods, alternative methods of producing lump-free CWS starch have been described. One employs heat-moisture treatment of a mixture of granular starch, a surfactant containing a fatty acid moiety and (optionally) a gum.214 A process for making a corn starch product giving a uniform viscous dispersion when added to boiling water employs heating a mixture of starch, surfactant and water, followed by microwave radiation.215 Compositions that gel at low solids concentrations were prepared by complexation of starches of moderate (20-30%) amylose content with emulsifiers.216... 

Sharypova, L.A., Niehaus, K., Scheidle, H., Holst, O., Becker, A. Sinorhizobium meliloti acpXL mutant lacks the C28 hydroxylated fatty acid moiety of lipid A and does not express a slow migrating form of lipopolysaccharide. J Biol Chem 278 (2003) 12946-12954. 

Studies carried out by Kopp and Jurenitsch (1981) on the biosynthesis of cap-saicinoids in C. annuum var. annuum established that valine, isoleucine and leucine were direct precursors of the respective even- and odd-numbered branched fatty acid moieties of the capsaicinoids. 

Kopp, B. and Jurenitsch, J. (1981) Biosynthesis of capsaicinoids in Capsicum annuum var. annuum. II. Formation of the fatty acid moiety of the capsaicinoids from L-valine, L-leucine and L-isoleucine. Planta-Medica 43(3), 272-279. 

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