Phospholipids Phosphorus

Almost all the starches investigated contain some phosphorus.124-126 In addition to phospholipids, phosphorus is also commonly found in starch as monostarch phosphate esters.6,7 Inorganic phosphate is present in some starches.124-126 Monostarch phosphate esters and phospholipids have different effects on starch paste properties.133,135 Monostarch phosphate esters, found in potato, shoti and other starches,6,7,136-140 increase paste clarity and paste viscosity.79 Little phosphate monoester is found in cereal starch.121,124,141,142 Phospholipids, found in normal cereal starches (e.g. wheat, rice and maize) decrease paste clarity and viscosity.133 31P-nmr spectroscopy has... 

As is evident from the patterns in Figure 3-2, the sulfuric acid (char) spray will detect all organic carbon-containing lipids whereas the phosphorus spray will detect only phospholipid phosphorus-containing lipids. In addition to these sprays, of course, the TNS reagent will react with all lipids and is very effective in locating various types of compounds on a plate. 

Quantitative Phospholipid Phosphorus Assay of Thin-Layer Chromatograms... 

Values for individual lipids are percentage of total phospholipids phosphorus. 

The relative resistance of sphingomyelin to alkaline hydrolysis has been used to some extent as a method for estimating the sphingomyelin content of tissues (75) and of lecithins and cephalin (37,45,103). Lecithin and cephalin are quantitatively hydrolyzed into acid-soluble phosphorus compounds by normal KOH at 37 C. within 24 hours. Thus, the difference between the total phospholipid phosphorus and the saponifiable phosphorus represents the amount of sphingomyelin phosphorus. 

Two methods, the one based on the alkali lability of RNA and the other on the acid lability of both RNA and DNA, appeared simultaneously in 1945 and have provided the analytical foundation for much of the recent research activity revolving about nucleic acids. The former of these methods is that of Schmidt and Thannhauser (abbreviated here as ST) (91) which depends upon the selective conversion of RNA phosphorus to organic acid-soluble phosphorus (mononucleotides) by alkali after removal of acid-soluble phosphates and of phospholipid phosphorus (16 et ante). The method of Schneider (S) (93) extracts the same lipid-free protein precipitate with hot trichloroacetic or perchloric (95) acid which solubilizes both RNA and DNA the estimation of each in the mixture utilizes specific colorimetric reactions for the (purine) ribose and desoxyribose moieties. These two methods will be discussed in connection with the combined method which follows. 

Step 2. Removal of Phospholipids. The tissue residue is suspended in 1.0 ml. of water, mixed with 4.0 ml. of 96% ethanol, and centrifuged. The residue is resuspended in 5.0 ml. of ethanol, and centrifuged. It is then extracted three times with three portions of 3 1 alcohol. ether at room temperature with brief stirring. The combined extracts constitute the phospholipid phosphorus fraction. 

Figure 7.42 Solubilization of microsomal constituents by increasing concentrations of (a) deoxycholate (b) cetyltrimethylammonium bromide Protein (O), chol terol (A), phospholipid phosphorus ( ), and Na -ion-stimulated adenosine triphosphatase ( ). Diagrams show the percentage of this constituent in the supernatant of the microsomal suspensions after treatment, as described by Bradford et al [194].

Yeast cells were treated with snail gut enzymes to form protoplasts and were disrupted by passage through a French pressure cell. Subcellular fractions were prepared and incubated with 2[ H]glycerol-3-phosphate for 30 min, as described by Cobon et al. The results are expressed as molar % phospholipid phosphorus. 

Although research laboratories use generally sophisticated analytical methods such as GLC to analyse and quantify lipid samples, chemical derivatizations are often used in hospitals. For these methods, the lipid samples are derivatized to yield a product which can be measured simply and accurately - usually by colour. Thus, total triacylglycerol, cholesterol or phospholipid-phosphorus can be quantitated conveniently without bothering with the extra information of molecular species, etc. which might be determined by more thorough analyses. 

Phosphatidic acids not only are intennediates in the biosynthesis of triacylglycerols but also are biosynthetic precursors of other members of a group of compounds called phosphoglycerides or glycerol phosphatides. Phosphorus-containing derivatives of lipids are known as phospholipids, and phosphoglycerides are one type of phospholipid. 

Phospholipids A lipid containing phosphorus which on hydrolysis yields... 

Phosphine(s), chirality of, 314 Phosphite, DNA synthesis and, 1115 oxidation of, 1116 Phospholipid, 1066-1067 classification of, 1066 Phosphopantetheine, coenzyme A from. 817 structure of, 1127 Phosphoramidite, DNA synthesis and, 1115 Phosphoranc, 720 Phosphoric acid, pKa of, 51 Phosphoric acid anhydride, 1127 Phosphorus, hybridization of, 20 Phosphorus oxychloride, alcohol dehydration with. 620-622 Phosphorus tribromide, reaction with alcohols. 344. 618 Photochemical reaction, 1181 Photolithography, 505-506 resists for, 505-506 Photon, 419 energy- of. 420 Photosynthesis, 973-974 Phthalic acid, structure of, 753 Phthalimide, Gabriel amine synthesis and, 929... 

A large number of combinations are theoretically possible and a lot of these structures are actually used in practice. We know that nature makes use of this variety, e.g., to form cell membranes by phospholipids. However, in daily practice the pool of hydrophobic raw material for the production of anionic phosphorus-containing surfactants is survey able. 

The lipid in muscle is composed primarily of triglycerides (depot fats) and of phospholipids (membrane components), and is a constituent which varies enormously not only in amount present, but also in properties such as degree of saturation (species dependent). The ash of lean meat is comprised of various minerals such as phosphorus, potassium, sodium, magnesium, calcium, iron and zinc Carbohydrate was not noted in the proximate composition because while some may be present, it is normally there in low concentration compared to the other constituents. Glycogen is the carbohydrate occurring in greatest concentration in muscle but is normally degraded soon after the animal is sacrificed. 

ECF. Note that phosphorus is the major anion within the cells. Given this distribution, serum phosphate concentration does not accurately reflect total body phosphorus stores. Phosphorus is expressed in milligrams (mg) or millimoles (mmol), not as milliequivalents (mEq). Because phosphorus is the source of phosphate for adenosine triphosphate (ATP) and phospholipid synthesis, manifestations of phosphorus imbalance are variable. 

Multinuclear MRS studies have demonstrated alterations in brains of schizophrenic patients. Phosphorus MRS studies, looking at both first-onset-unmedicated and chronic-medicated schizophrenia, consistently report alterations in the phospholipid profile in the frontal and temporal cortex [26-30]. Typically, phosphomonoester (PME) levels are lower than in controls, and phosphodiesters... 

Pettegrew, J. W., Keshavan, M. S., Panchalingam, K. et al. Alterations in brain high-energy phosphate and membrane phospholipid metabolism in first-episode, drug-naive schizophrenics. A pilot study of the dorsal prefrontal cortex by in vivo phosphorus 31 nuclear magnetic resonance spectroscopy. Arch. Gen. Psychiat. 48 563-568,1991. 

Several methods for the preparation of the parent compound in this system, tris(trimethylsilyl)phosphite, have been reported.114 118 The application of this and related reagents in reaction with alkyl halides has been reported and used for the preparation of a variety of phosphonic acid analogues of phospholipids.114119-124 Interestingly, alkyl chlorides appear to be more reactive with the silyl reagents than do alkyl iodides, a reversal of the normally observed trend with alkyl esters of the phosphorus acids. (The particular use of silyl phosphorus reagents for the synthesis of biologically significant compounds has... 

Briefly, liposomes (10mM) were incubated for 30minutes at 37°C for egg phosphatidylcholine (EPC) and at 60°C for HSPC-based liposomes with 50 X 10 dpm of methylamine (1 x 10 dpm/mole). At the end of incubation an aliquot of this mixture was passed down a Sephadex G-50 minispin column equilibrated in 10 mM histidine-sucrose buffer 10%, pH 6.7 buffer. Liposomes were eluted at the column void volume and separated from the unencapsulated methylamine. The concentration of liposomes in the original liposomal dispersion and in the void volume fraction was determined from the organic phosphorus (phospholipid) concentration (see section Lipid Quantification and Chemical Stability above) (10,49,53). 

Organic compounds that contain phosphorus include ATP, NADP, and the phospholipids. The phosphate group is often temporarily attached to other organic compoimds, such as pyruvate, as part of metabolic reactions, like glycolysis. As listed in Table 22.8, many of the phosphorus-containing biochemicals are found in seawater as a result of cell lysis and excretion. 

---