Lipid phosphoric acids

These lipid phosphoric acids possess a spectrum of biological activities of importance. The ether analogs, in particular, exhibit agonist activity at levels comparable to PAF. Unfortunately these compounds are found in very small amounts in biological tissues. As expected, this fact compromises their analytical evaluation. Nevertheless, there are certain procedures that can be undertaken to establish, with some certainty, their structural characteristics in naturally occurring samples. These approaches are discussed in the following sections. 

Though the lipid phosphoric acids are present in very low concentrations even in stimulated cells, it is possible with certain precautions to isolate them in good yields. Perhaps the most important experimental factor in a successful extraction is the inclusion of acid, usually 1 N HC1, in the extracting solvent. This is important because these acidic compounds normally exist as salts in the cell in order to extract them into a chloroform-rich fraction, for example, they must be converted to the free acid form. Given the satisfactory isolation of the total lipids, aliquots of this fraction can be assayed for total phosphorus by the macro procedure described in Chapter 4 or by the submicrogram method described by Bottcher et al. (1961). Two approaches can be used to separate the lysoPAs and the PAs from the other lipids as outlined on the following section. 

Sugiura, T., Tokumura, A., Gregory, L., Nouchi, T., Weintraub, S. T., and Hanahan, D. J. (1994) Biochemical characterization of the interaction of lipid phosphoric acids with human platelets comparison with platelet activating factor, Arch. Biochem. Biophys. 311, 358-368. 

Glycerophospholipid (Section 27.3) A lipid that contains a glycerol backbone linked to two fatty acids and a phosphoric acid. 

The development of monoalkyl phosphate as a low skin irritating anionic surfactant is accented in a review with 30 references on monoalkyl phosphate salts, including surface-active properties, cutaneous effects, and applications to paste and liquid-type skin cleansers, and also phosphorylation reactions from the viewpoint of industrial production [26]. Amine salts of acrylate ester polymers, which are physiologically acceptable and useful as surfactants, are prepared by transesterification of alkyl acrylate polymers with 4-morpholinethanol or the alkanolamines and fatty alcohols or alkoxylated alkylphenols, and neutralizing with carboxylic or phosphoric acid. The polymer salt was used as an emulsifying agent for oils and waxes [70]. Preparation of pharmaceutical liposomes with surfactants derived from phosphoric acid is described in [279]. Lipid bilayer vesicles comprise an anionic or zwitterionic surfactant which when dispersed in H20 at a temperature above the phase transition temperature is in a micellar phase and a second lipid which is a single-chain fatty acid, fatty acid ester, or fatty alcohol which is in an emulsion phase, and cholesterol or a derivative. 

The intracellular and plasma membranes have a complex structure. The main components of a membrane are lipids (or phospholipids) and different proteins. Lipids are fatlike substances representing the esters of one di- or trivalent alcohol and two aliphatic fatty acid molecules (with 14 to 24 carbon atoms). In phospholipids, phosphoric acid residues, -0-P0(0 )-O-, are located close to the ester links, -C0-0-. The lipid or phospholipid molecules have the form of a compact polar head (the ester and phosphate groups) and two parallel, long nonpolar tails (the hydrocarbon chains of the fatty acids). The polar head is hydrophihc and readily interacts with water the hydrocarbon tails to the... 

Phosphonolipids (glycerophosphonolipids) found mainly in protozoans and marine invertebrates are lipids with phosphoric acid derivatives esterified to the glycerol backbone. 

These are the most common class of complex lipid (Figure 12.11) and contain a phosphoric acid residue (phosphate group) and two fatty acids esterified to glycerol. Attached to the phosphate group is an amino alcohol, sometimes referred to as the nitrogenous base, which may be either serine, choline or ethanolamine or sometimes the monomethyl or dimethyl derivatives of ethanolamine (Table 12.4). Alternatively, a polyhydroxy compound which is either glycerol, myo-inositol or one of their derivatives is attached instead... 

Treatment with hot organic solvents was the next step in the tissue fractionation, to remove lipid-phosphorous and breakdown lipid-protein interactions. In the Schneider procedure, nucleic acids were then extracted in hot dilute trichloroacetic or perchloric acid, leaving a protein residue with any phosphoprotein links still intact. This method was to become particularly useful when 3H thymidine became the preferred label for DNA in the early 1960s. For investigations where both RNA and DNA were to be examined the Schmidt-Thannhauser process was often chosen. Here the lipid-extracted material was hydrolyzed with dilute sodium hydroxide releasing RNA nucleotides and any hydroxyamino acid bound phosphorus. DNA could be precipitated from the extract but the presence in the alkaline hydrolysate of the highly labeled phosphate released from phosphoprotein complicated... 

Phlogiston a material once thought to be an element responsible for combustion Phospholipid lipid containing phosphorus derived from phosphoric acid Photochemical Oxidants air pollutants produced when hydrocarbons, nitrogen oxides, and other chemicals react under the influence of sunlight, for example, ozone, peroxyacylnitrates (PAN)... 

FIGURE 1-10 The organic compounds from which most cellular materials are constructed the ABCs of biochemistry. Shown here are (a) six of the 20 amino acids from which all proteins are built (the side chains are shaded pink) (b) the five nitrogenous bases, two five-carbon sugars, and phosphoric acid from which all nucleic acids are built (c) five components of membrane lipids and (d) o-glucose, the parent sugar from which most carbohydrates are derived. Note that phosphoric acid is a component of both nucleic acids and membrane lipids. 

Phosphopantothenylcysteine decarboxylases 753, 755 Phosphophoryns 442 Phosphoporin (PhoE) 411, 412s Phosphoric acid in lipids 380 pKa value of 99 Phosphorolysis, 593 Phosphorothioate... 

Phospholipids, components of every cell membrane, are active determinants of membrane permeability. They are sources of energy, components of certain enzyme systems, and involved in lipid transport in plasma. Because of their polar nature, phospholipids can act as emulsifying agents. The structure of most phospholipids resembles that of triglycerides except that one fatty acid radical has been replaced by a radical derived limn phosphoric acid and a nitrogen base. c.g.. choline or serine. 

In summary, phospholipids (phosphatides) comprise a group of lipid compounds that yield, upon hydrolysis, phosphoric acid, an alcohol, fatty acid, and a nitrogenous base. They are widely distributed throughout nature. 

Traditionally, fractionation of the lipid extract was accomplished using open glass columns containing rather coarse and irregular silicic acid particles (9). Neutral lipids were eluted by chloroform, glycolipids were recovered using acetone, and methanol was used to obtain the phospholipids. Thus, Mounts et al. isolated PL from 5 g of oil on a 10-g column of silica gel (60-200 mesh) by sequential elution with 200 ml of chloroform, 100 ml of acetone, 100 ml of methanol, and 100 ml of 0.1% phosphoric acid in methanol (28). The last two fractions were combined to recover the phospholipid fraction. 

Esters of phosphoric acid that contain fatty acid(s), an alcohol, and a nitrogen-containing base. See also Lipid. 

Fig. 14.7. A scheme of the bilayer lipid membrane. The black circles indicate the polar heads (the hydrophilic part) consisting of phosphoric acid, ethanol amine, and analogue derivatives. The wavy lines are the long alkyl chains of fatty acids (the hydrophobic part) (Reprinted from J. Koryta, Ions, Electrodes and Membranes, Fig. 83. Copyright J. Wiley Sons, Ltd. 1991. Reproduced with permission of J. Wiley Sons, Ltd.)...

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