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PubMed1994

Biochemical characterization of the interaction of lipid phosphoric acids with human platelets: comparison with platelet activating factor.

A series of lipid phosphoric acids, including 1-O-alkyl-2-lyso-glycerophosphoric acid, 1-O-acyl-2-lyso-glycerophosphoric acid, hexadecylpropanediolphosphoric acid, N-acyl-2-aminoethanolphosphoric acid, sphingosine phosphoric acid, and certain homologues and analogues, were synthesized and characterized by thin-layer chromatography, fast-atom bombardment mass spectrometry, and their ability to aggregate human platelets. The presence of a receptor for these lipid phosphoric acids that is distinct from the PAF receptor is strongly suggested from experiments involving a desensitization procedure, platelet-activating factor (PAF) receptor antagonists, and inhibitors of the lipid phosphoric acids. The unique features of the interaction of these lipid phosphoric acids with platelets include: (a) evidence for a separate receptor(s) for this diverse group of synthetic compounds, (b) no requirement for stereospecificity (i.e., no glycerol backbone), and (c) a structural requirement for a long-chain hydrocarbon residue covalently bound to a phosphoric acid residue. In the interaction of these compounds with the platelet, it is mandatory that extracellular Ca2+ and ADP be present for maximum biological activity. The potential involvement of a lipid phosphoric acid receptor, which could form a component of the activation pathway associated with various lysophospholipids and analogues, such as PAF, via a phospholipase D activation, is discussed.

Blood Platelets↗
PubMed1976

Enzymatic hydrolysis of 1-monoacyl-SN-glycerol-3-phosphoryl-choline (1-lysolecithin) by phospholipases from peanut seeds.

Hydrolysis of 1-lysolecithin (1-acyl glycerophosphorylcholine [1-acyl GPC]) by preparations of phospholipase D from peanut seeds was investigated. 1-Lysolecithin was hydrolyzed at a much slower rate than phosphatidylcholine (lecithin). Although Ca+2 ions are required for the cleavage of lecithin by the enzyme, their effect on the hydrolysis of lysolecithin depended upon the concentration of the substrate: at 0.2 mM 1-lysolecithin, Ca+2 ions increased the reaction rates, whereas at concentrations of the substrate lower than 0.1 mM, Ca+2 ions were inhibitory. A broad pH activity curve between 5 and 8 was obtained with higher rates in the alkaline range, both in the absence and presence of Ca+2 ions. The increased hydrolysis of lysolecithin due to Ca+2 was noticed over the entire pH range. Upon storage of the enzyme solutions at 4 C, decreased rates of hydrolysis of lecithin were observed, with t 1/2 values of ca. 50 and 100 days depending on the purity of the preparation. During the same period, no reduction occurred in the activity of these preparations on lysolecithin as substrate. The effects of Ca+2 ions and the analysis of the products of 1-acyl GPC cleavage by the enzyme preparations revealed the presence of more than one enzyme and the formation of the following compounds: lysophosphatidic acids (1 acyl glycerophosphoric acids), free fatty acids, glycerophosphorylcholine, and choline. The possible pathways leading to the degradation of lysolecithin and the formation of these products include reactions catalyzed by lysophospholipase A1 (lysophosphatidylcholine 1-acyl hydrolase, E.C. 3.1.1.5) and a phosphodiesterase (L-3-glycerylphosphorylcholine glycerophosphohydrolase, E.C.3.1.4.2), in addition to phospholipase D (phosphatidyl-choline phosphatidohydrolase, E.C. 3.1.4.4).

Arachis↗
PubMed1967

The chemical nature of the products obtained by the action of cabbage-leaf phospholipase D on lysolecithin: the structure of lysolecithin.

1. Lysolecithin, prepared by the action of snake-venom phospholipase A on ovolecithin, when incubated with Savoy-cabbage phospholipase D, in the presence of Ca(2+) ions, gave two degradation products (designated A and B) in the form of their calcium salts. 2. These calcium salts were separated quantitatively by solvent fractionation and converted into the corresponding sodium salts. 3. Substance B proved to be a lysophosphatidic acid of conventional structure (1-monoacyl-l-3-glycerophosphoric acid). When the phosphate group was removed by means of prostatic acid phosphomonoesterase, a 1-monoglyceride was formed quantitatively. Alkaline hydrolysis gave the theoretical yield of l-3-glycerophosphate. 4. Substance A, on the other hand, had all the properties expected for a cyclic phosphate of a 1-monoglyceride. It was unaffected by phosphomonoesterase. On alkaline hydrolysis, the acyl group was removed and ring opening of the presumed cyclic phosphate group gave an approximately equimolar mixture of 2- and l-3-glycerophosphates. 5. The structures of substances A and B confirm lysolecithin as 1-monoacyl-l-3-glycerylphosphorylcholine.

Acid Phosphatase↗
PubMed1977

Analogs of natural lipids. IV. Synthesis and properties of cyclopentanoid analogs of phosphatidic acid.

A new series of phosphatidic acid analogs has been synthesized in which the glycerol moiety of diacylglycerophosphoric acid is replaced by each of the three isomeric cyclopentane-1,2,3-triols (1,3/2, DL-1,2/3, and 1,2,3/0). Of the seven possible configurational and positional phosphatidic acid analogs of this series, five isomers have been obtained and characterized by spectroscopic methods and microanalysis. Four of the five isomers are 1-(or 3-)phosphoryl derivatives, while the fifth is a 2-phosphate. The analogs were prepared in configurationally pure form by unequivocal synthetic procedures involving selectively blocked intermediates: acyl migration was avoided by the use of mild deblocking procedures. The anhydrous lipid products, all of which are dipalmitoyl esters, are solids indefinitely stable at room temperature in the free acid or potassium salt form; they have chromographic mobility and melting points similar to dipalmitoyl glycerophosphoric acid the dipotassium salts bind water of hydration tenaciously, remaining hydrated after drying in vacuo at 100 degrees C. NMR spectra of dimethyl esters of some of the analogs show nonequivalence of the two methyl groups, consistent with the diastereotopic nature of those groups. In addition to their intrinsic interest as conformationally restricted acidic lipids, the analogs are now available as starting materials for the synthesis of the more complex acidic and amphoteric lipids required for our exploitation of these cyclopentanoid analogs as unique probes for the study of lipid-lipid and protein-lipid interactions.

Chemical Phenomena↗
PubMed1981

Novel polar lipids from the methanogen Methanospirillum hungatei GP1.

The methanogenic bacterium Methanospirillum hungatei GP1 has been shown to contain two unusual phosphoglycolipids (phosphoglycolipid I and phosphoglycolipid II) that account for 64% (by wt.) of the total cellular lipids. These lipids are derivatives of the dibiphytanyldiglycerol tetraether. One of the free hydroxyls of this tetraether is esterified with glycerophosphoric acid and the other is linked glycosidically to a disaccharide with structure alpha-Glcp-(1 leads to 2)-beta Gal phi in phosphoglycolipid I and beta-Gal phi-(1 leads to 6)-beta Gal phi in phosphoglycolipid II. Smaller amounts of the sn-2,3-diphytanylglycerol analog of phosphatidylglycerol and diglycosyldiphytanylglycerol ethers (DGD-I and DGD-II) containing the same disaccharide residues as in phosphoglycolipid I and phosphoglycolipid II, respectively, were identified, together with very small amounts of diglycosyldibiphytanyldiglycerol tetraethers (DGT-I and DGT-II) containing the same disaccharide residues as in phosphoglycolipid I and phosphoglycolipid II, respectively. A biosynthetic pathway involving head-to-head condensation of phosphatidylglycerol with DGD-I or DGD-II to form phosphoglycolipid I or phosphoglycolipid II, respectively, is proposed.

Carbohydrate Conformation↗
PubMed1981

Novel complex polar lipids from the methanogenic archaebacterium Methanospirillum hungatei.

The methanogenic archaebacterium Methanospirillum hungatei contains two unusual phosphoglycolipids that account for 64 percent of the total cellular lipids. These lipids are derivatives of the dibiphytanyl diglycerol tetraether, previously identified in methanogens. One of the free hydroxyls of this tetraether is esterified with glycerophosphoric acid, and the other is linked glycosidically to a disaccharide. The two phosphoglycolipids may function as covalently bonded lipid bilayers to impart stability and rigidity to methanogen membranes.

Cell Membrane↗
PubMed1994

[Experience regarding the use of arginine-lysine-lactose treatment in menopausal osteoporosis].

Two matched groups of postmenopausal patients were treated respectively with calcitonin or calcitonin and an arginine-lysine-glycerophosphoric acid-lactose association. The rationale underlying this therapy took the form of data in the literature which indicated an action of these amino acids and lactose on calcium absorption and on the metabolism of protein components in the skeletal structure. The following tests were performed: mineralometric evaluation, evaluation of painful symptoms and intake of pain-relieving drugs, serum levels of calcium, phosphorus, alkaline phosphatase, osteocalcin, parathormone, and calciuria and hydroxyproline. These parameters were assayed at the beginning and end of treatment which lasted six months. The results, or in other words the comparison between the two groups, basal or after treatment, and the values recorded before and after treatment in each group, enable the authors to affirm that the administration of the arginine-lysine-glycerophosphoric acid-lactose association leads to an increase in bone density and plasma osteocalcin, a reduction in painful symptoms and analgesic intake, and a reduction in the serum levels of parathromone and hydroxyproline. Data reported in the literature support the conclusion that the results obtained are the consequence of an improved intestinal absorption calcium. It is highly probable that the protein components of the association administered, arginine-lysine-glycerophosphoric acid-lactose, also exercise a direct action on osteoblasts and on the metabolism of bone matrix protein components.

Adult↗
PubMed1977

Histochemical and ultrastructural study of the parafollicular (C) cells in the thyroid of the gerbil, Meriones unguiculatus.

A histochemical and electron-microscopic study has been done on the parafollicular (C) cells of the thyroid in the gerbil. Histochemical tests revealed the characteristic presence of alpha-glycerophosphoric dehydrogenase and the presence of phenolic groups and indoleamines. Acid phosphatase levels were similar to those observed in the apical cytoplasm of the follicular cells. Electron microscopy revealed characteristic presence of noncisternal rough endoplasmic reticulum, well-developed Golgi apparatus, numerous prosecretory granules and a few electrondense mature secretory granules. Most characteristic of these cells was the presence of numerous, large, electron-lucent vesicles which often were packed in the cytoplasmic processes that were located subjacent to the follicular cells and close to the blood capillaries. Significance of these histochemical and ultrastructural findings is emphasized particularly in regard to the presence of monoamines and their possible role in the release of calcitonin and thyroxin.

Acid Phosphatase↗
PubMed1977

Biochemical background of atherosclerotic heart lesion in an experiment.

The authors investigated enzymic systems and corresponding substrate cycles that transport hydrogen across the mitochondrial membrane in a myocardium with experimental cholesterol-induced atherosclerosis. Sensitive spectrophotometric methods were used for assessing the activities of cytoplasmic and mitochondrial enzymes: lactate and alpha-glycerphosphate dehydrogenases, and of characteristic mitochondrial enzymes: glutamate and beta-hydroxybutyrate dehydrogenases. Specific enzymological methods were used in determining the concentrations of lactic, pyruvic, glycerophosphoric, dihydroacetonephosphoric, malic, oxaloacetic, glutamic, alpha-ketoglutaric, acetoacetic, and beta-hydroxybutyric acids. The cytoplasmic NAD/NADH quotient was calculated. The investigators found a reduction of enzymic activities in the "shuttle" transport system studied, marked deviations from normal levels of their substrates, and a reduction of the NAD/NADH quotient by the factor 0.56. All these phenomena represent a biochemical background of a complex of symptoms characterizing severe myocardial lesion in experimental atherosclerosis.

Animals↗