Phospholipids fractionation

The greatest portion of the lipids in barley kernel is nonpolar lipids (67-78%). The compositions of lipids in the embryonic axis, bran endosperm, and hull fractions of hulless barley caryopses were determined by Price and Parsons (124) (Table 27). Neutral lipids were predominant in all fractions. Phospholipid content of barley hull was lower than that of the bran endosperm and embryonic axis. The hull fraction contained the highest glycolipid amount among the grain fractions. 

The four major plasma lipid fractions (phospholipids, cholesteryl esters, triglycerides, and free fatty acids) exhibited similar changes in response to the fish-oil diet. In the phospholipid fraction, the n-3 fatty acids increased from 0.4% to 34% of total fatty aicds in the fish oil diet. EPA increased from 0% to 19%, accounting for 55 percent of the total increase. Linoleic acid reciprocally decreased from 36% to 5% and total n-6 fatty acids from 48% to 12% of total fatty acids. In cholesteryl esters, n-3 fatty acids increased from 0.2% to 36%. An increase in EPA from 0% to 31% accounted for 86% of the increase, a much greater proportion than in phospholipids, whereas DHA only increased from 0% to 4%. The decline in n-6 fatty acids from 77% to 23% was largely accounted for by a decrease in linoleic acid from 73 % to 17%. Similar changes were seen in the triglycerides and free fatty acid fractions. 

Myelin is approximately 75% lipid and 25% protein. Carbohydrate residues are associated with both the lipid and the protein components of myelin. High proportions of cholesterol, phospholipid, and glycolipid are found in the lipid fractions. Phospholipids include ethanolamine phosphatides, phosphatidylserine, and phosphatidylinositol glycolipids include both neutral (cerebroside, sulfatide, galactosyldiglyceride) and polar (gangliosides, especially GMj and GMJ lipids. A classification and discussion of the metabolism of brain lipids is beyond the scope of this article readers are referred to Lajtha (1969), Davison (1968), Awasthi and Srivastava (1980), and Suzuki (1981). 

PC forms a lamellar layer in the interface between oil and water, different to the reversed hexagonal phase of PE or the hexagonal phase of lysophospholipids (Figure 10.4) [25]. This knowledge is used for the successful application of lecithins with adapted, modified or fractionated phospholipid composition. The different phase structures at the interface influence the emulsion formation and stability. 

Phospholipids. For the removal of ionic contaminants from raw zwitterionic phospholipids, most lipids were purified twice by mixed-bed ionic exchange (Amberlite AB-2) of methanolic solutions. (About Ig of lipid in lOmL of MeOH). With both runs the first ImL of the eluate was discarded. The main fraction of the solution was evaporated at 40°C under dry N2 and recryst three times from n-pentane. The resulting white powder was dried for about 4h at 50° under reduced pressure and stored at 3°. Some samples were purified by mixed-bed ion exchange of aqueous suspensions of the crystal/liquid crystal phase. [Kaatze et al. J Phys Chem 89 2565 7955.]... 

No discussion of the use of biotransfarmation in lipid chemistry would be complete without some mention of chemical transformation relating to fatty adds. Fatty adds are a major component of the lipid fraction of organisms. They are mainly found as components of triglycerides and phospholipids, although they may occur in smaller quantities as free fatty adds or as esters of other moieties. Fatty adds, either as free adds or as esters, are valuable commodities in the food and cosmetics industries. They may also serve as precursors of a variety of other compounds. 

A molecular variation of plasma membrane has been reported by Puccia et al. Reduction of total lipids (XL) content and significant variations of triglyceride (TG) and phospholipids (PL) fractions were observed as a consequence of exposure of C. intestinalis ovaries to TBTCl solutions. In particular, an evident TG decrease and a PL increase were observed, which probably provoked an increment in membrane fluidity, because of the high concentration of long chain fatty acids and, as a consequence, PL. This could be a cell-adaptive standing mechanism toward the pollutants, as observed in Saccharomyces cerevisiae. Also the increase in the content of the polyunsaturated fatty acids (PUPA), important in the synthesis of compounds such as prostaglandin which are present in the ovary in a stress situation, was probably a consequence of a defense mechanism to the stress provoked by the presence of TBTCl. 

Plasma lipids consist of triacylglycerols (16%), phospholipids (30%), cholesterol (14%), and cholesteryl esters (36%) and a much smaller fraction of unesteri-fied long-chain fatty acids (free fatty acids) (4%). This latter fraction, the free fatty acids (FFA), is metaboh-cally the most active of the plasma hpids. 

Figure 38, Patterns obtained from the extract of 10 fd of serum for lipid fraction by thin-layer chromatography. In sequence, starting from the bottom, phospholipids, pee cholesterol, cholesterol aniline as an internal standard, triglycerides, and cholesterol esters. The free fatty acids occur between cholesterol and the internal standard and are only barely visible in the print, on the extreme right. They are readily visible, normally, to the eye.

Using PTLC six major fractions of lipids (phospholipids, free sterols, free fatty acids, triacylglycerols, methyl esters, and sterol esters) were separated from the skin lipids of chicken to smdy the penetration responses of Schistosoma cercaria and Austrobilharzia variglandis [79a]. To determine the structure of nontoxic lipids in lipopolysaccharides of Salmonella typhimurium, monophosphoryl lipids were separated from these lipids using PTLC. The separated fractions were used in FAB-MS to determine [3-hydroxymyristic acid, lauric acid, and 3-hydroxymyristic acids [79b]. 

Preparative TLC may be applied to cleanup selected compound fractions separated from geochemical samples by such methods as HPLC, as Aries et al. [113] has described. To analyze phospholipids and nonphospholipids in sediments, organic matter was extracted and extracts LC-fractionated to obtain polar fractions. At the... 

Quantitative estimates of microbial and community structure by means of analysis of the phospholipid fraction have been performed on. sediments, water (135), and dust (136) as well as. soil (137-141). The method is applicable to the study of mixed populations of varying degrees of complexity and is relatively straightforward to perform. A selection of studies involving the analysis of fatty acid profiles of environmental samples are outlined in Table 6. 

V. Lindahl, A. Frostegard, L. Bakkhen, and E. Baath, Phospholipid fatty acid composition of size fractionated indigenous soil bacteria. Soil Biol. Biochem. 29 1565 (1997). 

L. Zelles, A. Palojarvi, E. Kandeler, M. VonLut/.ow, K. Winter, Q. Y. Bai. Changes in. soil mierobial properties and phospholipid fatty acid fractions after chloroform fumigation. Soil Biol. Biochem. 29 1325 (1997). 

Experiments with monkeys given intramuscular injections of a mineral oil emulsion with [l-14C] -hexa-decane tracer provide data illustrating that absorbed C-16 hydrocarbon (a major component of liquid petrolatum) is slowly metabolized to various classes of lipids (Bollinger 1970). Two days after injection, substantial portions of the radioactivity recovered in liver (30%), fat (42%), kidney (74%), spleen (81%), and ovary (90%) were unmetabolized -hexadecane. The remainder of the radioactivity was found as phospholipids, free fatty acids, triglycerides, and sterol esters. Essentially no radioactivity was found in the water-soluble or residue fractions. One or three months after injection, radioactivity still was detected only in the fat-soluble fractions of the various organs, but 80-98% of the detected radioactivity was found in non-hydrocarbon lipids. 

Most of the permeabilities of the bases decrease steadily as the phospholipid fraction increases. There are some significant exceptions. Metoprolol, which is only moderately permeable in the DOPC lipid, becomes appreciably permeable in 10% soy lecithin. But at the 68% soy level, this molecule also shows reduced transport. 

However, when up to 74% phospholipid fractions are used, severe experimental problems arise. With lipophilic sample molecules, the use of concentrated phospholipid artificial membranes leads to two unwanted effects (1) near-complete membrane retention (90-100%) and (2) highly diminished permeability (extinguished in some cases). Both of these effects are presumably due to excessive drug-membrane binding. 

It has been suggested [6] that these unusual sterols, especially in those cases where these unusual sterols comprise the entire sterol content of the organisms, likely replace conventional sterols as cell-membrane components. Evidence for this comes from subcellular fractionation and subsequent analysis of two marine sponges [10]. The sterol composition of the membrane isolates was found to be identical to that of the intact sponge. Most common variation of the marine sterol is in the side-chain, situated deep in the lipophylic environment of the phospholipid bilayer. This suggests that unusual fatty acids might accompany the sterols, and indeed this is often the case [8]. 

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