Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P50583 (asymmetrical)
 12,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

(1) The carboxyl group of fatty acids has a very low pK value, which is shifted into the physiological pH range when they are incorporated in a phospholipid membrane. As a result of a pH increase the surface charge and surface potential of the membrane increase. (2) The titration of the carboxyl group was observed with condensed phase radioluminescence. This technique uses the electron emitted by the tritiated membrane probe (oleic acid or cholesterol) to excite a fluorophore also incorporated in the bilayer. (3) The phase transition of dimyristoyl phosphatidylcholine vesicles labelled within 12-(9-anthroyloxy)stearic acid was measured by condensed phase radioluminescence at different pH values. (4) We related the condensed phase radioluminescence signal to the asymmetrical distribution of the fluorophore between the inner and outer layer of the lipid membrane which is induced by the repulsion of the negatively charged fatty acids. (5) We showed that the condensed phase radioluminescence signal is proportional to the protonation of the carboxyl group. On this basis, the broadening of the titration curve can be explained as an effect of the self-induced membrane potential calculated using the Gouy-Chapman theory. (6) Ca2+ drastically reduces the flip-flop rate of fatty acids across the membrane and also caused a decrease in the asymmetric distribution. (7) We concluded that a fatty acid can act as a membrane surface buffer. The pK value of 12-(9-anthroyloxy)stearic acid in a dimyristoyl phosphatidylcholine membrane is 7.0 +/- 0.3. (8) We discuss the results with respect to aggregation, fusion and clustering.
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PMID:The effect of fatty acids on the surface potential of phospholipid vesicles measured by condensed phase radioluminescence. 722 90

Exosomes are small vesicles secreted from multivesicular bodies, which are able to stimulate the immune system leading to tumour cell eradication. We have analysed lipids of exosomes secreted either upon stimulation from rat mast cells (RBL-2H3 cells), or constitutively from human dendritic cells. As compared with parent cells, exosomes displayed an enrichment in sphingomyelin, but not in cholesterol. Phosphatidylcholine content was decreased, but an enrichment was noted in disaturated molecular species as in phosphatidylethanolamines. Lyso(bis)phosphatidic acid was not enriched in exosomes as compared with cells. Fluorescence anisotropy demonstrated an increase in exosome-membrane rigidity from pH 5 to 7, suggesting their membrane reorganization between the acidic multivesicular body compartment and the neutral outer cell medium. NMR analysis established a bilayer organization of exosome membrane, and ESR studies using 16-doxyl stearic acid demonstrated a higher flip-flop of lipids between the two leaflets as compared with plasma membrane. In addition, the exosome membrane exhibited no asymmetrical distribution of phosphatidylethanolamines. Therefore exosome membrane displays a similar content of the major phospholipids and cholesterol, and is organized as a lipid bilayer with a random distribution of phosphatidylethanolamines. In addition, we observed tight lipid packing at neutral pH and a rapid flip-flop between the two leaflets of exosome membranes. These parameters could be used as a hallmark of exosomes.
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PMID:Mast cell- and dendritic cell-derived exosomes display a specific lipid composition and an unusual membrane organization. 1496 43

Seed oils from new recombinant high-stearic sunflower lines (Helianthus annuus L.) have been characterized. These new lines were generated by crossing high stearic acid lines between themselves or by crossing them with standard and high-oleic sunflower lines. Of the novel lines generated, the lines CAS-29 and CAS-30 are on a standard background and contain up to 34.5% of stearic acid. In contrast, CAS-15 and CAS-33 are on a high oleic acid background and contain only 24.9 and 17.4% of stearic acid, respectively. The stearic acid contents of lines CAS-19 and CAS-20 are 10.0 and 21.5%, respectively, and they have only one of the two genes that control the high stearic acid trait. In accordance with their vegetable origin, these lines have a low percentage of stearic acid in the sn-2 position of the TAGs, from 0.6 to 2.1%. The amount of disaturated TAGs increases with the stearic acid content, from 1.8% in the standard line to between 5.1% in CAS-20 and 38.5% in CAS-29. There was also a concomitant reduction in triunsaturated TAGs, which were reduced to levels as low as 8.4% in CAS-29, as opposed to the 67.9% that they constitute in the standard line RHA-274. The asymmetrical distribution of the saturated fatty acids between the sn-1 and sn-3 TAG positions ranges from 0.26 to 0.36, being lower in those lines with higher oleic acid content.
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PMID:Oils from improved high stearic acid sunflower seeds. 1596 13

A novel silver nanoparticles (AgNPs)/chitosan composite dressing with asymmetric wettability surfaces was successfully prepared via a simple two-step method for biomedical applications as wound healing materials. First, AgNPs were assembled into the chitosan sponge which was prepared by lyophilization process. Then one side of the sponge was modified by a thin layer of stearic acid. The incorporation of AgNPs into chitosan dressing could enhance the antibacterial activity against drug-sensitive and drug-resistant pathogenic bacteria. The asymmetric surface modification endows the dressing with both highly hydrophobic property and inherent hydrophilic nature of chitosan. The hydrophobic surface of the dressing shows waterproof and antiadhesion for contaminant properties, whereas the hydrophilic surface preserves its water-absorbing capability and efficiently inhibits the growth of bacteria. Furthermore, the AgNPs/chitosan composite dressing displays improved moisture retention and blood clotting ability compared to the unmodified dressings. Cytocompatibility test evaluated in vitro and in a wound infection model illustrates the nontoxic nature of the composite dressing. More importantly, the in vivo wound healing model evaluation in mice reveals that the asymmetric AgNPs/chitosan dressing promotes the wound healing and accelerates the reepithelialization and collagen deposition. The silver accumulation in mice body treated by the composite dressing is far lower than that of the clinically used Acasin nanosilver dressing treated mice. This work indicates the huge potential of the novel AgNPs/chitosan wound dressing with asymmetrical wettability for clinical use.
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PMID:Novel Asymmetric Wettable AgNPs/Chitosan Wound Dressing: In Vitro and In Vivo Evaluation. 2680 Feb 83

The wings of insects such as cicadas and dragonflies have been found to possess nanostructure arrays that are assembled from fatty acids. These arrays can physically interact with the bacterial cell membranes, leading to the death of the cell. Such mechanobactericidal surfaces are of significant interest, as they can kill bacteria without the need for antibacterial chemicals. Here, we report on the bactericidal effect of two of the main lipid components of the insect wing epicuticle, palmitic (C16) and stearic (C18) fatty acids. Films of these fatty acids were re-crystallised on the surface of highly ordered pyrolytic graphite. It appeared that the presence of two additional CH2 groups in the alkyl chain resulted in the formation of different surface structures. Scanning electron microscopy and atomic force microscopy showed that the palmitic acid microcrystallites were more asymmetric than those of the stearic acid, where the palmitic acid microcrystallites were observed to be an angular abutment in the scanning electron micrographs. The principal differences between the two types of long-chain saturated fatty acid crystallites were the larger density of peaks in the upper contact plane of the palmitic acid crystallites, as well as their greater proportion of asymmetrical shapes, in comparison to that of the stearic acid film. These two parameters might contribute to higher bactericidal activity on surfaces derived from palmitic acid. Both the palmitic and stearic acid crystallite surfaces displayed activity against Gram-negative, rod-shaped Pseudomonas aeruginosa and Gram-positive, spherical Staphylococcus aureus cells. These microcrystallite interfaces might be a useful tool in the fabrication of effective bactericidal nanocoatings.
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PMID:Bactericidal activity of self-assembled palmitic and stearic fatty acid crystals on highly ordered pyrolytic graphite. 2868 88