Letter: Palmitic acid/stearic acid ratio in lecithin and fetal maturity.
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Amniotic Fluid↗
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Chemical identification of lipid components in the membranous form of rat liver alkaline phosphatase.
Membranous and soluble forms of rat liver alkaline phosphatase were selectively prepared by extracting microsomes with n-butanol at pH 8.5 and 5.5, respectively, and purified in homogeneous forms by the method previously established (Miki et al. (1986) Eur. J. Biochem. 160, 41-48). When subjected to polyacrylamide gel electrophoresis, the two forms migrated to the same position in the presence of sodium dodecyl sulfate, while the membranous form remained at the top of gels in the absence of the detergent. Treatment of the membranous form with phosphatidylinositol-specific phospholipase C resulted in its conversion to a soluble form with the same electrophoretic mobility even in the absence of the detergent as that of the soluble form extracted at pH 5.5. Automated Edman degradation analysis showed that the two forms have the same N-terminal amino acid sequence up to the 30th residue determined. Chemical analyses of hydrolysates of the two forms by gas-liquid chromatography demonstrated that the membranous form contains palmitic acid, stearic acid, and inositol, while the soluble form contains inositol but is devoid of the fatty acids. Taken together, these results suggest that rat liver alkaline phosphatase is covalently attached to phosphatidylinositol acylated with palmitic acid and stearic acid, which functions as the membrane-anchoring domain of the enzyme molecule.
Alkaline Phosphatase↗
Gel-to-inverted hexagonal (L beta-HII) phase transitions in phosphatidylethanolamines and fatty acid-phosphatidylcholine mixtures, demonstrated by 31P-NMR spectroscopy and x-ray diffraction.
The phase behaviour of distearoyl- and dihexadecylphosphatidylethanolamine at high salt concentration and of dipalmitoylphosphatidylcholine + 66 mol% palmitic acid at pH 4.0 have been studied by high-field 31P-NMR spectroscopy and X-ray diffraction. In saturated NaCl, dihexadecylphosphatidylethanolamine undergoes a reversible transition at 74 degrees C directly from the lamellar gel phase L beta to the inverted hexagonal HII phase. A similar transition is observed at 78.4 degrees C for distearoylphosphatidylethanolamine in saturated NaCl (cooling scan). The single, sharp calorimetric transition at 61 degrees C observed in dipalmitoylphosphatidylcholine + 66 mol% palmitic acid at pH 4.0 also corresponds to a transformation directly from the lamellar gel to the inverted hexagonal phase, without an intervening fluid lamellar phase.
Calorimetry, Differential Scanning↗
The prolonged persistence of mycoplasmas in culture.
Mycoplasma fermentans organisms in medium containing 20% horse serum multiplied to 10(7)-10(10) ccu/ml within 5 days at 37 degrees C and were dead usually after 9 days. There was no growth in medium without serum, nor in such medium with the addition of cholesterol or palmitic acid or both, but in some experiments addition of bovine plasma albumin (BPA) increased the number of organisms by up to 1000-fold and some remained viable for up to 84 days. BPA and cholesterol or BPA, palmitic acid and cholesterol more often enhanced growth, in terms of the maximum number of organisms and their survival, than did the addition of BPA alone. The maximum number of organisms in such supplemented serum-free media was usually at least ten-fold less than in medium with horse serum, but some organisms remained viable for up to 131 days. Survival of Ureaplasma urealyticum was also longer in the supplemented serum-free medium than in standard horse-serum medium. The possible factors affecting persistence of mycoplasmas in culture are discussed in relation to these observations.
Animals↗
Molecular architecture and biophysical properties of phospholipids during thermal adaptation in fish: an experimental and model study.
Phospholipids from livers of carps (Cyprinus carpio L.) adapted to winter (5 degrees C) and summer (25 degrees C) temperatures were isolated, and the fatty acid composition of total phospholipids, as well as molecular species composition of diacyl phosphatidylcholines and ethanolamines, were determined. Order parameter of 5-doxyl stearic acid and steady-state fluorescence anisotropy of different anthroyloxy fatty acids--[2-, 12(N-9-anthroyloxy)stearic acid and 16(N-9-anthroyloxy)palmitic acid--embedded in native and synthetic (16:0/16:0, 16:0/22:6, 18:0/22:6, 18:1/22:6, 20:4/20:4, 22:6/22:6 phosphatidylcholines and 16:0/18:1, 18:1/22:6 phosphatidylethanolamines) phospholipid vesicles was also determined between -30 and 30 degrees C and 5 and 30 degrees C, respectively. There is an accumulation of 1-monoenoic, 2-polyenoic diacyl phosphatidylcholine and ethanolamine with a concomitant reduction of 1-stearoyl,2-docosahexaenoyl species in the cold-adapted state. Despite a 30% accumulation of long-chain polyunsaturated fatty acids in phospholipids in cold, there is only a 5 degrees C downshift in the solid-gel to liquid-crystalline phase transition temperature (-8 vs. -13 degrees C). Vesicles from total phospholipids of cold-adapted fish proved to be more disordered in all segments than from the warm-adapted ones when assayed using 2,12-(N-9-anthroyloxy)stearic and 16-(N-9-anthroyloxy)palmitic acid. Vesicles made from purified phosphatidylcholines showed the same pattern, but they were more disordered than the corresponding total phospholipids. This could be modelled using mixed phospholipid vesicles made of synthetic 16:0/22:6 phosphatidylcholine (75%) and either 18:1/22:6 phosphatidylethanolamine (25%) vs. 16:0/18:1 phosphatidylethanolamine (25%) and comparison of the anisotropy parameters of 100% 16:0/22:6 and 100% 18:1/22:6 phosphatidylcholine vesicles. Mixing either 16:0/18:1 (25%) or 18:1/22:6 (25%) phosphatidylethanolamines to 18:0/22:6 (75%) phosphatidylcholine shifted down or up, respectively, the transition temperature of vesicles compared to 100% 18:0/22:6 vesicles assayed by electron spin resonance spectroscopy using 5-doxylstearic acid. It is concluded that it is not the gross amount of long-chain polyunsaturated fatty acids in phospholipids, but rather their specific combination with cis delta 9 monounsaturated fatty acids in the position sn-1, especially in phosphatidylethanolamines, that is important in determining the physical properties of biomembranes in relation to adaptational temperature.
Adaptation, Physiological↗
Expression of a functionally active cardiac fatty acid-binding protein in the yeast, Saccharomyces cerevisiae.
The unicellular eukaryotic microorganism, Saccharomyces cerevisiae, transformed with a plasmid containing a cDNA fragment encoding bovine heart fatty acid-binding protein (H-FABP) under the control of the inducible yeast GAL10 promoter, expressed FABP during growth on galactose. The maximum level of immunoreactive FABP, identical in size to native protein as judged from SDS-polyacrylamide gel electrophoresis, was reached after approximately 16 hours of induction. Analysis of particulate and soluble subcellular fractions showed that FABP was exclusively associated with the cytosol. FABP expressed in yeast cells was functional as was demonstrated by its capacity to bind 14C-oleic acid in an in vitro assay. Growth of the transformants on galactose as the carbon source was significantly retarded at 37 degrees C. Whereas the fatty acid pattern of total lipids was not altered in transformed cells, desaturation of exogenously added 14C-palmitic acid was significantly reduced both at 30 and 37 degrees C. The lowest percentage of radioactively labeled unsaturated fatty acids was found in the phospholipid fraction.
Carbon Radioisotopes↗
Fatty acid transfer between multilamellar liposomes and fatty acid-binding proteins.
A simple experimental system was developed for studying the movement of long-chain fatty acids between multilamellar liposomes and soluble proteins capable of binding fatty acids. Oleic acid was incorporated into multilamellar liposomes containing cholesterol and egg yolk lecithin and incubated with albumin or hepatic fatty acid-binding protein. It was found that the fatty acid transferred from the liposomes to either protein rapidly and selectively under conditions where phospholipid and cholesterol transfer did not occur. More than 50% of the fatty acid contained within liposomes could become protein bound, suggesting that the fatty acid moved readily between and across phospholipid bilayers. Transfer was reduced at low pH, and this reduction appeared to result from decreased dissociation of the protonated fatty acid from the bilayer. Liposomes made with dimyristoyl or dipalmitoyl lecithin and containing 1 mol per cent palmitic acid were used to show the effect of temperature on fatty acid transfer. Transfer to either protein did not occur at temperatures where the liposomes were in a gel state but occurred rapidly at temperatures at or above the transition temperatures of the phospholipid used.
Carbon Radioisotopes↗
Palmitoylation of CD44 interferes with CD3-mediated signaling in human T lymphocytes.
We studied the interactions between CD44 and four different monoclonal anti-CD44 antibodies. All four monoclonal anti-CD44 antibodies studied (P3H9, Bu52, IM.7, and GKW.A3) act in synergy with human anti-CD2 antibodies in stimulating normal human peripheral blood lymphocytes to proliferate. GKW.A3 and IM.7 but not P3H9 or Bu52 inhibited the proliferation of normal human peripheral blood lymphocytes stimulated by anti-CD3. Interestingly, only GKW.A3 and IM.7 stimulated the incorporation of [3H]palmitic acid and palmitoylation of CD44 molecules by normal human peripheral blood lymphocytes. The two monoclonal anti-CD44 antibodies (P3H9 and Bu52) that failed to inhibit anti-CD3 induced proliferation also failed to induce the incorporation of [3H]palmitic acid. More importantly, the inhibitory effects of GKW.A3 were reversed in the presence of cerulenin, an inhibitor of protein palmitoylation. Therefore, palmitoylation of CD44 may interfere with anti-CD3 mediated signaling pathways. These data support the hypothesis that palmitoylation of cell surface receptors may play an active role in receptor and receptor interactions and signal transduction in normal human T lymphocytes.
Antibodies, Monoclonal↗
The interaction of free fatty acids in radioimmunoassays for reverse triiodothyronine.
We have investigated the effect of FFA on the RIA of rT3 because of our previous findings of a correlation between serum rT3 values and increased FFA concentrations during prolonged exercise and reports of interference by FFA in other thyroid hormone assays. Apparent rT3 values increased by 19% and 34% in in vivo studies of acute lipolysis in subjects 5 min post exercise or 10 min post heparin, respectively, while T3 and T4 concentrations were unchanged. Varying concentrations of palmitic acid were added in vitro to four normal sera, and the increase in FFA concentration correlated significantly with the increase in apparent rT3 values. The mean +/- SE of the regression slope was 9.3 +/- 1.8 ng/dl rT3/mM FFA (r = 0.96 +/- 0.02). The addition of linoleic acid produced a similar effect. T3 and T4 concentrations were unchanged. The interaction of FFA in the rT3 RIA was unrelated to the procedure used to separate the assay, to the concentration of 8-anilino-1-napthalene-sulfonic acid in the assay buffer, to FFA binding directly to the antisera or to use of a particular antisera. The magnitude of the effect was similar in charcoal-treated sera, and the addition of 2 mM palmitic acid to the assay standard curve decreased the y intercept but did not alter the slope, suggesting an interaction of rT3 with FFA, rather than change in affinity of the antisera.
Energy Intake↗
Geotrichum candidum NRRL Y-553 lipase: purification, characterization and fatty acid specificity.
Lipases from Geotrichum candidum NRRL Y-553 are of interest because of their unique specificity for cis-9-unsaturated fatty acids relative to both stearic and palmitic acids. The lipases were partially purified by chromatography on Octyl Sepharose, AG MP-1 macroporous anion exchanger, and chromatofocusing resin. The preparation was found to contain multiple, glycosylated lipases varying slightly in pI (pI 4.88, 4.78, 4.65, 4.57 and 4.52) as judged by both activity and silver staining. The molecular mass determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis was 64 kilodaltons for the main species, with minor species of 60 and 57 kilodaltons present as well. The specificity of the crude lipases for hydrolysis of 4-methylumbelliferyl esters of oleic vs. palmitic acid was 20-to-1. The specificity of the purified, partially separated lipases was similar to that of the crude preparation. Thus the lipases could be used even in crude form for the hydrolysis and restructuring of triacylglycerols on a large scale.
Geotrichum↗
Structure-activity relationship of reversibly lipidized peptides: studies of fatty acid-desmopressin conjugates.
PURPOSE: To synthesize a series of reversible fatty acid-desmopressin (DDAVP) conjugates and to study their structure-activity relationship as anti-diuretic drugs. METHODS: Seven fatty acid conjugates of DDAVP were prepared using various reversible lipidization reagents as described in our previous reports. All products were purified by acid precipitation and/or size-exclusion chromatography. Reversed-phase HPLC was used to evaluate their purity and lipophilicity. The anti-diuretic efficacy of these fatty acid conjugates was assessed in vasopressin-deficient Brattleboro rats. Four selected conjugates, i.e., DPA, DPH, DPD and DPP (acetic, hexanoic. decanoic, and palmitic acid conjugate, respectively), along with DDAVP itself were used in Caco-2 cell uptake studies and their degradation and the regeneration of active DDAVP were investigated using an in vitro liver slice metabolic system coupled with a HPLC assay. RESULTS: All fatty acid-DDAVP conjugates were more lipophilic than DDAVP as examined by HPLC analyses. When cysteine was used as the linker, the capacity index (k', a measure of lipophilicity) of the conjugates was linearly correlated with the number of carbons in the fatty acid chain. The anti-diuretic activity of the conjugates was correlated with the length of the fatty acid chain, with C10 as the minimal requirement for possessing the enhanced anti-diuretic activity. Among the seven fatty acid conjugates, palmitic acid conjugate was the most potent DDAVP derivative. Removal of carboxyl group from the cysteine linker completely abolished the enhancement of the activity. The extent of cellular uptake also positively correlated with the lipophilicity of the conjugates. The metabolism of DDAVP, DPH, DPD, and DPP by liver slices all followed first order kinetics with half-life of 0.30, 0.01, 0.06 and 3.44 hr, respectively. The degradation rates of DPH and DPD in the liver slice incubation were much faster than that of DDAVP and therefore an accumulation of regenerated DDAVP in the media was observed. In contrast, DPP was metabolized much slower than DDAVP and, consequently, no significant accumulation of regenerated DDAVP could be detected. CONCLUSION: Conjugation of DDAVP with fatty acids increased the lipophilicity and the anti-diuretic activity of this peptide drug. The anti-diuretic activity of lipidized DDAVP was dependent on the chain length of the fatty acid, as well as the structure of the linker in the conjugate. The preservation and enhancement of the in vivo antidiuretic activity of the conjugates is most likely due to a combination of an improved pharmacokinetic behavior and a concurrent regeneration of active DDAVP in tissues.
Animals↗
Inhibitory effect of FO-1561 (S-adenosyl-L-methionine sulfate tosylate) on phospholipase A2.
The mechanism of the protective effect of FO-1561 (S-adenosyl-L-methionine sulfate tosylate) on mitochondria was investigated using rat heart muscle. FO-1561 stimulated CO2 production from palmitic acid in the mitochondria, indicating an increase in energy production. FO-1561 inhibited mitochondrial swelling induced by Ca2+ added exogenously or by addition of snake venom phospholipase A2. Moreover, FO-1561 inhibited phospholipase A2 activity directly. These results suggested that FO-1561 blocked mitochondrial swelling by inhibiting endogenous phospholipase A2 activity and so preventing decrease in palmitic acid oxidation.
Animals↗
Mechanism for adaptive modification during cold acclimation of phospholipid acyl chain composition in Tetrahymena. I. Principal involvement of deacylation-reacylation.
The purpose of the present studies with in vivo isotope labeling was to explore the mechanism by which the fatty acyl composition of membrane phospholipids was altered quickly after a downward temperature-shift in Tetrahymena pyriformis. 1. When 39 degrees C-grown Tetrahymena cells were shifted to 15 degrees C, unsaturated fatty acids, especially gamma-linolenic acid, were increased, with compensating decrease of palmitic acid in phospholipids. 2. However, in the [32P]Pi-prelabeled cells, the specific radioactivities of major membrane phospholipids, phosphatidylethanolamine, phosphatidylcholine and 2-aminoethylphosphonolipid, were not changed within 10 h after shift-down. Furthermore, in the [14C]palmitic acid-prelabeled cells, the specific radioactivities toward phospholipids also did not change after temperature-shift. 3. After the shift, the rate of incorporation of [14C]acetate into fatty acids was reduced to less than one-tenth and the principal fatty acid newly synthesized was linoleic acid, and palmitic and gamma-linolenic acids were also formed to almost same degree. 4. In contrast, when cells prelabeled with both [32P]Pi and [14C]palmitic acid were shifted to 15 degrees C and then linoleic and gamma-linolenic acids, which are known to increase during cold acclimation, were added to the medium, the 14C/32P ratios of major phospholipids were progressively decreased until 5 h after the shift. These results suggest the mechanism for the alteration of phospholipid fatty acyl composition at lowered growth temperature by which preexisting fatty acids of membrane phospholipids would be deacylated and then, after modification to adequate unsaturated fatty acids by desaturation and/or elongation, be reacylated again into lysophospholipids.
Acclimatization↗
Palmitoylation of the rat mu opioid receptor.
We examined whether the mu opioid receptor was palmitoylated and attempted to determine sites of palmitoylation. Following metabolic labeling with [3H]palmitic acid and immunoaffinity purification of the mu opioid receptor, SDS-PAGE and fluorography revealed a broad labeled band with Mr of approximately 80 kDa in CHO cells stably expressing the rat mu receptor, but not in CHO cells transfected with the vector alone, indicating that the mu receptor is palmitoylated. Activation of the receptor with morphine did not affect the extent of palmitoylation. Hydroxylamine or dithiothreitol treatment removed most of the radioactivity, demonstrating that [3H]palmitic acid is incorporated into Cys residue(s) via thioester bond(s). Surprisingly, mutations of the only two Cys residues in the C-terminal domain did not reduce [3H]palmitic acid incorporation significantly. Thus, unlike many G-protein coupled receptors, the palmitoylation site(s) of the rat mu opioid receptor do(es) not reside in the C-terminal domain.
Amino Acid Sequence↗
Effect of nitric oxide on albumin-palmitate binding.
Bovine serum albumin (albumin) was modified by treatment with nitric oxide (NO) to form S-nitrosoalbumin. Analysis of the reduced sulfhydryl groups showed that more than 99% of the albumin was converted to S-nitrosoalbumin. Using a 1:1 molar ratio of protein:palmitate, the unbound palmitate fraction in the presence of S-nitrosoalbumin was determined to be greater (28%) than in the presence of albumin as determined by heptane: water partitioning. NO degradation products neither affected the palmitate heptane:water partition ratio in the absence of binding protein nor the hepatocyte uptake of [3H]palmitic acid. The equilibrium association constants (Ka) for albumin-palmitate and S-nitrosoalbumin-palmitate complexes were determined using the stepwise equilibrium model. The Ka for the first and second palmitate binding sites were (4.6 +/- 1.2) x 10(8) M-1 and (3.3 +/- 0.5) x 10(7) M-1 and (3.1 +/- 0.9) x 10(8) M-1 and (1.3 +/- 0.8) x 10(8) M-1 for albumin and S-nitrosoalbumin, respectively. Thus, the increased unbound fraction of palmitate in the presence of S-nitrosoalbumin was apparently due to a decreased binding affinity at the first high-affinity binding site. Palmitate uptake by hepatocyte suspensions was 27% higher in the presence of S-nitrosoalbumin as compared with albumin. This increase paralleled the increased unbound palmitate fraction. When the albumin concentration was adjusted to account for the increased unbound fraction, there was no difference in the palmitate uptake rates between albumin and S-nitrosoalbumin. Our findings indicate that under conditions where NO concentrations are high (e.g. cirrhosis) and extensive S-nitrosylation of serum albumin occurs, the decreased ligand binding ability of S-nitrosoalbumin may be an important consideration when modeling drug uptake in pathological states.
Animals↗
Long-term performance of high-rate anaerobic reactors for the treatment of oily wastewater.
Complex oily wastewater from a food industry was treated in three different UASB reactors at different operating conditions. Although all three systems achieved fat, oil, and grease (FOG) and COD removal efficiencies above 80% at an organic loading of 3 kg COD/m3 x d, system performance deteriorated sharply at higher loading rates, and the presence of high FOG caused a severe sludge flotation resulting in failure. Initially, FOG accumulated onto the biomass which led to sludge flotation and washout of biomass. The loss of sludge in the bed increased the FOG loading to the biomass and failure ensued. Contrary to previous findings, accumulation of FOG rather than influent FOG concentrations or volumetric FOG loading rate was the most importantfactor governing the high-rate anaerobic reactor performance. The critical accumulated FOG loading was identified as 1.04 +/- 0.13 g FOG/g VSS for all three reactors. Furthermore, FOG accumulation onto the biomass was identified mainly as palmitic acid (>60%) whereas the feed LCFA contained only 30% of palmitic acid and 50% of oleic acid.
Anaerobiosis↗
Solution-phase and solid-phase syntheses of enzyme inhibitor RK-682 and antibiotic agglomerins.
The enzyme inhibitor RK-682 (5R)-(+)-1 was prepared in solution and on a solid support from (2R)-glycerates in five steps and ca. 40% overall yield. Key steps were a ring-closing tandem addition-Wittig alkenation reaction of the respective protected or immobilized glycerates with the ylide Ph(3)PCCO and the 3-acylation of the tetronic acids thus obtained with palmitic acid. A similar route extended by a mesylation-elimination sequence led to antibiotic agglomerins A-C 2 featuring 3-acyl-5-methylidenetetronic acid structures.
4-Butyrolactone↗
The characterization and distribution of hexahydropolyprenyl esters in cultures of Aspergillus fumigatus Fresenius.
The total mycelial lipid of Aspergillus fumigatus was analysed and over half of its hexahydropolyprenol was shown to be esterified with fatty acids. Comparison of the fatty acid content of the prenyl esters with the sterol ester and the total lipid indicated a marked predominance of saturated fatty acids in the polyprenyl esters. The predominant acids esterified to the prenols were palmitic acid, linoleic acid, oleic acid, lignoceric acid, stearic acid and palmitoleic acid. Most of the unesterified polyprenol was found in the mitochondrial fraction, but the esterified prenol was equally distributed throughout the cell fractions. This distribution was unlike that found for ergosteryl ester in the same tissue.
Alcohols↗