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PubMed2004

Association of sugar-based carboranes with cationic liposomes: an electron spin resonance and light scattering study.

The possibility of cationic (di-oleoyltrimethylammonium propane, DOTAP)/(L-alpha-dioleoylphosphatidyl-ethanolamine, DOPE) liposomes to act as carriers of boronated compounds such as 1,2-dicarba-closo-dodecaboran(12)-1-ylmethyl](beta-D-galactopyranosyl)-(1-->4)-beta-D-glucopyranoside and 1,2-di-(beta-D-gluco-pyranosyl-ox)methyl-1,2-dicarba-closo-dodeca-borane(12) has been investigated by Electron Spin Resonance (ESR) of n-doxyl stearic acids (n-DSA) and Quasi-Elastic Light Scattering (QELS). Both these carboranes have potential use in Boron Neutron Capture Therapy (BNCT), which is a targeted therapy for the treatment of radiation resistant tumors. They were shown to give aggregation both in plain water and in saline solution. Carborane aggregates were, however, disrupted when DOTAP/DOPE liposome solutions were used as dispersing agents. The computer analysis of the ESR spectra from carborane-loaded liposomes allowed to establish an increase of the order degree in the liposome bilayer with increasing carborane concentration, together with a decreased mobility. The same discontinuities of both correlation time and order parameter with respect to temperature variations were observed in carborane-containing and carborane-free liposomes. This suggested that a homogeneous dispersion of nitroxides and carboranes occurred in the liposome bilayer. The ESR line shape analysis proved that no dramatic changes were induced in the liposome environment by carborane insertion. QELS data showed that the overall liposome structure was preserved, with a slight decrease in the mean hydrodynamic radius and increase in polydispersity caused by the guest molecules.

Boron Neutron Capture Therapy↗
PubMed1996

Inhibition of oxidation of low density lipoprotein by vitamin E and related compounds.

The oxidation of low density lipoprotein (LDL) was carried out aiming specifically at elucidating the anti-oxidant action of alpha-tocopherol. Lipophilic and hydrophilic azo compounds and copper induced the oxidation of LDL similarly to give cholesterol ester and phosphatidylcholine hydroperoxides as major products. The antioxidant potency of alpha-tocopherol in LDL was much poorer than in homogeneous solution. Doxyl stearic acids were used as spin probe and incorporated in LDL. The rate of reduction of doxyl nitroxide in LDL by ascorbate decreased with increasing distance from the LDL surface. From the competition between the spin probe and alpha-tocopherol in scavenging radical, it was found that the efficacy of radical scavenging by alpha-tocopherol became smaller as the radical went deeper into the interior of LDL. On the other hand, 2,2,5,7,8-pentamethyl-6-chromal spared the spin label regardless of the position of nitroxide. The antioxidant activity of chromanols against LDL oxidation increased with decreasing length of isoprenoid side chain at the 2-position. All these results were interpreted by location and low mobility of alpha-tocopherol in LDL. The tocopherol mediated propagation was observed notably at low rate of radical flux, but this was suppressed by reductant such as ascorbic acid and ubiquinol.

Amidines↗
PubMed1996

Effects of free fatty acids on the binding of bovine and human serum albumin with steroid hormones.

Recent studies have shown that, in addition to free steroid hormones, those bound to albumin in plasma may also be available to tissues. In this report, the effects of free fatty acids (FFA) on the binding of steroids to albumin were compared for the cases of bovine serum albumin (BSA) and human serum albumin (HSA). The apparent association constant, Ka, was estimated from the changes in the equilibrium partition coefficient of steroids between the aqueous/hexane phases caused by the addition of albumin to the aqueous phase. In the case of BSA, Ka for progesterone and testosterone increased upon binding of FFA (myristic, palmitic and stearic acid) to BSA and the maximum value of Ka for these steroids could be attained by 3--4 mol of FFA bound per mol BSA. Furthermore, the elution profiles of gel-filtration chromatography clearly showed that progesterone and testosterone are easily liberated from the steroid/BSA complexes and that FFA potentiates the binding of these steroids to BSA. In the case of HSA, the binding affinities of progesterone and testosterone were not greatly affected by bound FFA. On the other hand, the affinities of ethynylestradiol to both BSA and HSA were unaffected below 4 mol of FFA binding per mol.

Animals↗
PubMed1984

In vitro synthesis of mycolic acids by the fluffy layer fraction of Bacterionema matruchotii.

Biosynthetic activity for mycolic acid occurred in the fluffy layer fraction but not in the 5000g supernatant of Bacterionema matruchotii. With [1-14C]palmitic acid as precursor for the in vitro system, the predominant product was identified as C32:0 mycolic acid by radio-gas-liquid chromatographic (radio-GLC) and gas chromatographic/mass spectroscopic analyses; if [1-14C]stearic acid was used, two major radioactive peaks appeared on GLC: one corresponding to the peak of (C34:0 + C34:1) mycolic acids and the other to (C36:0 + C36:1) mycolic acids. By pyrolysis/radio-GLC analysis, C32:0 mycolic acid synthesized by [1-14C]palmitic acid was pyrolyzed at 300 degrees C to form palmitaldehyde (the mero moiety) and methyl palmitate (the branch moiety). The pH optimum for the incorporation of [1-14C]palmitate into bacterionema mycolic acids was 6.4 and the reaction required a divalent cation. The in vitro system utilized myristic, palmitic, stearic and oleic acids (probably via their activated forms) well as precursors, among which myristic and palmitic acids were more effective than the rest. Avidin showed no effect on the biosynthesis of mycolic acid from 14C-palmitate whereas cerulenin, a specific inhibitor of beta-ketoacyl synthetase in de novo fatty acid synthesis, inhibited the reaction at a relatively higher concentration. Thin-layer chromatographic analysis of lipids extracted from the reacting mixture without alkaline hydrolysis showed that both exogenous [1-14C]fatty acid and synthesized mycolic acids were bound to an unknown compound by an alkali-labile linkage and this association seemed to occur prior to the condensation of two molecules of fatty acid.

Actinomycetaceae↗
PubMed1987

Hormonal effects on mitochondrial respiration: potential role of endogenous lipolytic activities.

Hormonal effects on heart mitochondrial metabolism are investigated by comparing respiratory rates, Ca2+ uptake capacity, and lipolytic activities of mitochondria isolated from control rats to those of mitochondria isolated from thyroparathyroidectomized animals. Two biochemically and morphologically distinct populations of heart mitochondria are prepared--one derived from the region of the cell directly beneath the sarcolemma (subsarcolemmal mitochondria), the other originally between the myofibrils (interfibrillar mitochondria). Subsarcolemmal mitochondria isolated from normal rat cardiac tissue have both lower respiratory rates and Ca2+ uptake capacity than do interfibrillar mitochondria. However, when these mitochondrial populations are isolated from hearts from thyroparathyroidectomized rats, there is a selective increase in the maximal ability of the subsarcolemmal mitochondria to accumulate Ca2+, which is accompanied by a proportionate increase in their maximal respiratory rates. Neither Ca2+ uptake capacity nor respiratory rates are similarly increased in the interfibrillar mitochondria. Cytochrome contents and mitochondrial protein recoveries are not significantly changed in either of these mitochondrial preparations. The relationship between these selective increases in respiratory properties of the subsarcolemmal mitochondria to endogenous lipolytic activities is also investigated. It was previously demonstrated that, in the absence of Ca2+, both the rate and extent of formation of free fatty acids from endogenous phospholipids is greater in subsarcolemmal than interfibrillar mitochondria (J. W. Palmer et al. (1981) Arch. Biochem. Biophys. 211, 674-682). In this study it is shown that lipolysis is also more sustained in the subsarcolemmal mitochondria when Ca2+ is added. In the subsarcolemmal mitochondria isolated from thyroparathyroidectomized rats, however, the rates of release of stearic acid and oleic acid are reduced in both the presence and absence of Ca2+. In the presence of added Ca2+, the rate of release of arachidonic acid is also decreased compared to control subsarcolemmal mitochondria, suggesting that the expressed activity of Ca2+-activated phospholipase A2 is lower in those mitochondria isolated from the thyroparathyroidectomized animals, in which respiratory rates and Ca2+ uptake capacity are increased.

Animals↗
PubMed2006

Dietary gangliosides enhance in vitro lipid uptake in weanling rats.

BACKGROUND: The intestine adapts morphologically or functionally in response to environmental stimuli. Dietary lipids modify brush border membrane (BBM) permeability and nutrient transporter activities. Gangliosides (GANG) are glycolipids in human milk that are present only in low amounts in infant formula. Exogenous GANG are incorporated into cell membranes and increase their permeability. The objective of this study was to determine whether feeding a GANG-enriched diet alters in vitro intestinal lipid absorption. METHODS: Weanling rats were fed either (1) GANG-enriched diet; (2) diet enriched with polyunsaturated long-chain fatty acids; or (3) isocaloric control diet for 2 weeks, after which in vitro intestinal lipid uptake was measured. RESULTS: Feeding GANG did not alter weight gain or intestinal morphology. Enhanced uptake of stearic acid (18:0) in the ileum and stearic and linoleic acid (18:2) in the jejunum was not associated with a change in the abundance of the ileal lipid binding protein (ILBP), the intestinal fatty acid binding protein (I-FABP), or the liver fatty acid binding protein (L-FABP). CONCLUSION: We speculate that the enhanced uptake of long-chain fatty acids in weanling rats fed GANG may be caused by a modification in physical properties of the BBM.

Adaptation, Physiological↗
PubMed1991

Eicosanoid-dependent and -independent formation of individual [14C]stearoyl-labelled lysophospholipids in collagen-stimulated human platelets.

Low level collagen activation of platelets is mediated via the release of arachidonic acid (AA) from membrane phospholipids and the formation of thromboxane A2 (TxA2). To assess the specific phospholipids undergoing deacylation via phospholipase A2 thereby providing source(s) of releasable AA, we have measured the individual lysophospholipid formations in platelets prelabelled with [14C]stearic acid and incubated with a low level (2 micrograms/ml) or a high level (10 micrograms/ml) of collagen in the absence or presence of BW755C, a dual inhibitor of cyclooxygenase and lipoxygenase activities. Collagen activation resulted in the generation of [14C]stearoyl-labelled lysophosphatidylinositol (lysoPI), lysophosphatidylcholine (lysoPC), lysophosphatidylethanolamine (lysoPE) and lysophosphatidylserine. BW755C significantly inhibited these collagen-induced changes, suggesting that much of the lysophospholipid, and therefore AA release, was eicosanoid-mediated. At the lower level of collagen, considerable generation of [14C]lysoPE was maintained even in the presence of BW755C, suggesting an eicosanoid-independent degradation of phosphatidyl-ethanolamine. The TxA2-dependent release of AA was also investigated in U-46619-stimulated platelets. This TxA2 mimetic induced considerable formation of the 14C-labelled lysophospholipids, including lysoPI and lysoPC, but not lysoPE. These results suggest that an eicosanoid-independent degradation of phosphatidylethanolamine via phospholipase A2 at lower collagen levels may provide a source of the initial AA for conversion to TxA2 and the subsequent deacylation of phosphatidylinositol, phosphatidylcholine, and also phosphatidylserine.

4,5-Dihydro-1-(3-(trifluoromethyl)phenyl)-1H-pyraz↗
PubMed2005

An approach to solvent screening for crystallization of polymorphic pharmaceuticals and fine chemicals.

It is desirable to have a systematic approach for predicting or interpreting the effect of the solvents on the production of polymorphs. A method based on the atomic electronegativity is suggested that calculates the partial charge distribution in the solute and solvent molecules. Using the calculated partial charges, correlations are developed to predict the hydrogen bonding ability of the solute and/or solvent molecules. The predictive capability of the proposed correlations is compared with the results of a quantum mechanics approach. Selection of the right solvent may play a significant role in the formation of a desirable polymorph or solvate. The most important properties of class 2 and 3 solvents of International Conference on Harmonization (ICH) for crystallization of polymorphic compounds are listed in this paper. The partial charge calculation has been used as a tool for analyzing the solvent impact on polymorphic isolation of two compounds: ranitidine hydrochloride (H2 receptor antagonist) and stearic acid (used as excipients or in coating the tablets).

Algorithms↗
PubMed1996

Phase behavior of artificial stratum corneum lipids containing a synthetic pseudo-ceramide: a study of the function of cholesterol.

The phase properties and structural characteristics of stratum corneum (SC) lipid lamellae have been a subject of considerable interest. To clarify the individual role of the stratum corneum constituent lipids, such as ceramides, free fatty acids, and cholesterol, we investigated the thermotropic properties and aggregation structures of a pseudo-ceramide/stearic acid (1/1 mole ratio)-cholesterol system, which is a simplified model for the natural lipids. Differential scanning calorimetry (DSC) detected decreases of melting entropies (delta Sm) by the incorporation of cholesterol into both anhydrous and hydrated equimolar mixture of pseudo-ceramide (SLE) and stearic acid. Moreover, there was a linear relationship between the cholesterol content and the melting entropies in the region of 0-33 mol% cholesterol for both the anhydrous and hydrate lipids. In addition, as the concentration of cholesterol increased, a liquid lateral packing (4.5 A) appeared in the wide-angle X-ray diffraction and the intensity of a hexagonal packing (4.15 A) decreased. The results from the present study strongly follow the idea that cholesterol can regulate the mobility of hydrocarbon chains of the natural stratum corneum lipid bilayer, which is primarily responsible for the barrier properties.

Calorimetry, Differential Scanning↗
PubMed1981

A spin label study of erythrocyte membranes during simulation of freezing.

Human erythrocytes were labeled with stearic acid spin labels, and no change was detected in membrane fluidity under hyperosmotic stress, going from isotonicity to about 3000 mOsm. Intact erythrocytes labeled with an androstane spin label and submitted to simulation of freezing show the onset of irreversible structural breakdown occurring in a saline solution at 2,000 mOsm. Ghosts labeled with maleimide spin label (4-maleimide-2,2,6,6-tetramethylpiperidinooxyl) when submitted to solutions of increasing osmolalities (pH 7.4), exhibit protein conformational changes that are irreversible after a simulated freeze-thaw cycle. After sonication of maleimide spin-labeled ghosts, membrane buried sulfhydryl groups become exposed. Such preparations showed behavior similar to the unsonicated when in saline hyperosmolal medium (pH 7.4). Such results suggest the ionic strength of the medium as the determining factor of the detected conformational changes. Maleimide spin-labeled ghosts in 300 mOsm saline solution (pH 7.4) were treated with ascorbic acid (spin destruction of nitroxides), and the kinetic analysis indicates that 65% of the labeled sites are located at the external interface of the membrane or in hydrophilic channels. Deformation and rearrangements of membrane components in solutions of increasing osmolalities apparently are related to protein conformational changes, on the outside surface of erythrocyte membranes, with a significant amount being structurally dissociated of lipids.

Androstanes↗
PubMed1995

Electron spin resonance studies of fatty acid-induced alterations in membrane fluidity in cultured endothelial cells.

Endothelial cell dysfunction has been implicated in the development of atherosclerosis. Of vital importance to the maintenance of endothelial cell integrity is the preservation of membrane functional and structural properties, such as membrane fluidity. The aim of this study was to develop a model for studying the relationship between endothelial cell integrity and membrane fluidity alterations in a well-defined cell culture setting. Alterations in membrane fluidity were assessed using electron spin resonance after labeling endothelial cells with the lipid-specific spin labels, CAT-16 and 12-nitroxide stearic acid. Endothelial cells were exposed to various 18-carbon fatty acids, i.e. stearic (18:0), oleic (18:1), linoleic (18:2), or linolenic (18:3), in addition to lipolyzed HDL (L-HDL) and benzyl alcohol. Membrane phospholipid fatty acid composition of endothelial cells supplemented with these fatty acids was analyzed using gas chromatography. All fatty acids, except 18:0, decreased membrane fluidity. A relationship between membrane fluidity and fatty acid compositional alterations in cellular phospholipids was observed. In particular, the arachidonic acid content decreased following exposure to 18:1, 18:2, or 18:3. Exposure of endothelial cells to L-HDL, lipoprotein particles which contain high levels of 18:1 and 18:2, also decreased membrane fluidity. The stabilization of cytoskeletal actin filaments by phalloidin partially prevented 18:2-induced increases in albumin transfer, thus implicating a cytoskeletal involvement in the 18:2-induced membrane fluidity changes involved in endothelial cell dysfunction. The present study shows that the exposure of endothelial cells to various lipids causes membrane fluidity alterations which may contribute to endothelial cell dysfunction and atherosclerosis.

Animals↗
PubMedDate not supplied

Methotrexate loaded solid lipid nanoparticles (SLN) for effective treatment of carcinoma.

Solid Lipid Nanoparticles (SLN) containing Methotrexate (MTX), an anticancer drug for intravenous administration was formulated and characterized. The SLN dispersions with MTX, stearic acid, and soya lecithin in the ratio of 1:4:1, 1:4:1.5, and 1:4:2, sodium taurodeoxycholate and distilled water were prepared by micro emulsification solidification method. The results show that the prepared MTX-SLN particles (with MTX-Stearic acid-Soya lecithin--1:4:2) have an average size of 270 nm with 51.3% drug entrapment. The in-vitro release was attained up to 15th h. The pharmacokinetic study reveals that the half-life and MRT of SLNs were higher than MTX solution. The life span of EAC (Ehrlich Ascite Carcinoma) bearing mice was increased when treated with MTX-SLNs (Methotrexate nanoparticles). These results clearly indicate that SLNs are a promising sustained release drug targeting system for lipophilic antitumour drugs.

Animals↗
PubMed1996

Spin label and 2H-NMR studies on the interaction of melanotropic peptides with lipid bilayers.

The interaction of the cationic tridecapeptide alpha-melanocyte stimulating hormone (alpha-MSH) and the biologically more active analog [Nle4, DPhe7]-alpha-MSH with lipid membranes was investigated by means of ESR of spin probes incorporated in the bilayer, and NMR of deuterated lipids. All spin labels used here, stearic acid and phospholipid derivatives labeled at the 5th and 12th position of the hydrocarbon chain, and the cholestane label, incorporated into anionic vesicles of DMPG (1,2-dimyristoyl-sn-glycero-3-phosphoglycerol) in the liquid-crystalline phase, indicated that both peptides decrease the motional freedom of the acyl chains. No peptide effect was detected with neutral lipid bilayers. Changes in the alpha-deuteron quadrupolar splittings and spin lattice relaxation time of DMPG deuterated at the glycerol headgroup paralleled the results obtained with ESR, showing that the peptides cause a better packing both at the headgroup and at the acyl chain bilayer regions. The stronger effect caused by the more potent analog in the membrane structure, when compared to the native hormone, is discussed in terms of its larger lipid association constant and/or its deeper penetration into the bilayer.

Amino Acid Sequence↗
PubMed1980

Perturbations to lipid bilayers by spectroscopic probes as determined by dielectric measurements.

Dielectric measurements on lecithin/cholesterol bimolecular lipid membranes have indicated that the series of extrinsic fluorescent probe molecules, the n-(9-anthroyloxy) fatty acids, cause significant perturbation to the bilayer structure at concentrations equivalent to those used in fluorescence experiments (0.1 mol%). Perturbations were observed in the capacitance and conductance of the electrically distinct substructural regions of the bilayer that were consistent with the putative location of the probe molecules. Inclusion of stearic acid decreased the thickness of the hydrocarbon region of the membrane, presumably by expanding the average surface area per unit membrane mass, and also significantly disrupted the surface regions. The attachment of the anthroyloxy moiety to position 2 of a fatty acid accentuated both these effects. Attachment at position 12 had the reverse effect by increasing the volume of the hydrocarbon region without further disturbance of the surface organisation. The 9-positioned probe had an intermediate effect. The degree of perturbation by the 2-positioned probe was dependent on the probe concentration within the range (probe:lipid) 1:1000 to 1:10 000. The technique therefore detects perturbation of structure at probe levels which are lower than those commonly used in fluorescence-labelling experiments.

Alkanes↗
PubMed1989

Fatty acyl coupled catalase.

Bovine liver catalase (hydrogen-peroxide:hydrogen peroxide oxidoreductase, EC 1.11.1.6) was derivatized by 9"(10")-[4'-(2-(4,6-dichloro-1,3,5-triazinyl) oxy)butoxy] stearic acid and the fatty acyl-coated enzyme was separated from native catalase and excess reagent by hydroxyapatite chromatography. The derivatization of catalase resulted in coupling the long-chain fatty acyl residues to lysine, histidine and arginine, while other amino acids remained essentially unaffected. The fatty acyl-coated enzyme was water soluble at pH greater than 7.0 but became octanol and ether soluble at pH less than 6.5. The derivatized enzyme retained 50-80% of the catalatic- and peroxidative-specific activities. The free carboxyl function of the coupled long-chain fattyl acyl residues could serve as substrate for ATP-dependent CoA-thioesterification catalyzed by the rat liver microsomal long-chain fatty acyl-CoA synthase.

Acylation↗
PubMed1990

Semiquinones derived from anthraquinone-containing antitumor drugs can partition into phosphatidylcholine bilayers.

Semiquinones derived from anthraquinone-containing antitumor drugs (doxorubicin, daunorubicin and 4'-epidoxorubicin) were generated by the hypoxanthine/xanthine oxidase system in argon-saturated phosphate buffer (pH 7.4) in the presence of egg-yolk phosphatidylcholine multilamellar vesicles (MLVs) containing 1 mol% of a doxylstearic acid (DSA) isomer. The destruction of the electron spin resonance signal corresponding to 5-, 12- and 15-DSA included in the MLVs follows pseudo-first-order kinetics. Higher rates of destruction are obtained for the 12-DSA isomer which indicates that these semiquinones can localize preferentially about the depth of the 12th position of stearic acid in membranes. It is demonstrated that DSA destruction is due to a reversible reduction of DSA to the hydroxylamine species. This work shows that anthracycline semiquinones can partition into phosphatidylcholine bilayers under anoxic conditions which may imply another pathway in their cytotoxic action.

Anthraquinones↗
PubMed1988

Rat proximal small intestinal Golgi membranes: lipid composition and fluidity.

The present studies were conducted to examine and characterize the lipid composition and physical state of the membrane lipids of rat proximal small intestinal Golgi membranes. Golgi membranes were purified from isolated enterocytes; lipids were extracted from these membranes and analyzed by thin-layer and gas-liquid chromatography. The 'static' and 'dynamic' components of fluidity of Golgi membranes and their liposomes were assessed by steady-state fluorescence polarization techniques utilizing r infinity and S values of 1,6-diphenyl-1,3,5-hexatriene and r values of DL-2-(9-anthroyl)- and DL-12-(9-anthroyl)stearic acid, respectively. Additional studies were also performed on these membranes, using benzyl and methyl alcohol, to examine the relationship between alterations in lipid fluidity and glycosphingolipid glycosyltransferase activities. The results of these studies demonstrated that: (1) the principal phospholipids and neutral lipids of intestinal Golgi membranes, respectively, were phosphatidylcholine, phosphatidylethanolamine and sphingomyelin, and unesterified cholesterol and fatty acids; (2) the major fatty acids of Golgi membranes were palmitic (16:0), stearic (18:0), linoleic (18:2), arachidonic (20:4) and oleic (18:1) acids; (3) fluorescence polarization studies using diphenylhexatriene detected a thermotropic transition at 24-26 degrees C in Golgi membranes and liposomes prepared from lipid extracts of these membranes; (4) benzyl alcohol (25 and 50 mM) but not methyl alcohol (50 mM) significantly increased the fluidity of these membranes; and (5) at these same concentrations, benzyl alcohol was also found to increase significantly the specific activity of UDP-galactosyllactosylceramide galactosyltransferase but not CMP-acetylneuraminic acid: lactosylceramide sialyltransferase. Methyl alcohol was not found to influence either enzyme's activity in these membranes.

Animals↗
PubMed1996

Alterations of lipoprotein fluidity by non-esterified fatty acids known to affect cholesteryl ester transfer protein activity. An electron spin resonance study.

The aim of the present study was to investigate the effect of saturated, monounsaturated and polyunsaturated non-esterified fatty acids (NEFA) on lipoprotein fluidity by using the electron spin resonance (ESR) method. The fluidity of the lipid phase of lipoproteins was evaluated by calculating from ESR spectra the S parameter of three different positional isomers of spin-labeled stearic acid incorporated into the lipoprotein. In non-enriched lipoproteins, S values were higher in high-density lipoprotein 3 (HDL3) than in low-density lipoprotein (LDL) indicating that the surface of HDL3 was more ordered. Prior incubation of lipoprotein particles with NEFA significantly reduced S values, indicating an increased lipoprotein fluidity as compared with non-supplemented homologous samples. In NEFA-enriched lipoproteins, the modifications in fluidity were shown to be dependent on the structure of the NEFA acyl carbon chains. Medium-chain fatty acids [lauric (12:0) and myristic (14:0) acids] appeared to be better fluidizing molecules as compared with both shorter [octanoic (8:0) and decanoic (10:0) acids] and longer [palmitic (16:0) and stearic (18:0) acids] homologues. In addition, introducing at least one double bond in the acyl carbon chain significantly increased the ability of NEFA to reduce S as compared with saturated homologues. In both LDL and HDL3, the extent of the modifications of the molecular mobility at the lipoprotein surface was dependent on the final NEFA/lipoprotein ratio. In conclusion, these results suggest that the ability of NEFA to modulate the activity of the cholesteryl ester transfer protein might relate in part to alterations in fluidity at the lipoprotein surface.

Carrier Proteins↗