La réaction de décarboxylation de l’acide palmitique en n-pentadécane a été étudiée en réacteur discontinu en présence de catalyseurs bimétalliques de type Ni-Me (où Me=Fe, Cu ou Ag) supportés sur charbon actif. Ces catalyseurs ont été préparés à l’aide d’un robot haut débit disponible sur la plateforme REALCAT de l’UCCS par déposition-précipitation en utilisant l’hydrazine comme agent réducteur afin de mieux maitriser la taille des nanoparticules métalliques, leur distribution et leur degré de réduction. Ces derniers ont été caractérisés par ICP, adsorption d’azote, XPS, XRD et TEM afin d’obtenir des informations relatives à leurs compositions, leurs propriétés texturales, surfaciques et morphologiques. Dans cette étude, l’optimisation du procédé catalytique a également été étudiée pour divers paramètres de réaction pour les catalyseurs les plus prometteurs. D’une part, l’impact de l’ajout d’un second métal sur les performances des catalyseurs à base de nickel a été étudié, et, d’autre part, l’effet de la température, de la durée de réaction, des concentrations initiales en réactifs, de l’atmosphère réactionnelle et de la masse de catalyseur utilisée ont été investiguées. Dans ce contexte, le catalyseur bimétallique 10%Ni10%Cu/C convertit complètement l’acide palmitique avec une sélectivité de 95 % en n-pentadecane à 320 °C sous une atmosphère contenant 10% de H2 dans N2 et pour une pression initiale de 20 bar. La réaction s’est déroulée pendant 6 h. Ce catalyseur a présenté une excellente stabilité après trois tests de recyclage consécutifs / The catalytic decarboxylation of palmitic acid to n-pentadecane was studied in a batch reactor in the presence of bimetallic Ni-Me catalysts (where Me = Fe, Cu or Ag) supported on activated carbon. These catalysts were prepared using a high-throughput robot of the REALCAT platform of UCCS by deposition-precipitation using hydrazine as reducing agent. These catalysts were characterized by ICP, N2 adsorption, XPS, XRD and TEM in order to obtain information relative to their compositions, textural properties, surfaces and morphologies. In this study, the optimization of the catalytic process was also investigated for various reaction parameters for the most promising samples. The main studied parameters were, on the one hand, the impact of the addition of a second metal on the performance of the nickel-based catalysts and, on the other hand, the effect of temperature, reaction time, initial reactant concentrations, atmosphere and mass of catalyst used. The conclusion of this study is that the 10%Ni10%Cu/C completely converts palmitic acid with a selectivity of 95 % to n-pentadecane in 6 h, at 320 °C under 10% H2 in N2 at an initial pressure of 20 bar. This catalyst exhibited excellent recyclability after three consecutive tests

Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-01-19T10:10:26Z No. of bitstreams: 1 charlesdiasdebrito.pdf: 2413607 bytes, checksum: f1809f4cce1cb76f35fa95ba6b716e99 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-01-25T17:43:32Z (GMT) No. of bitstreams: 1 charlesdiasdebrito.pdf: 2413607 bytes, checksum: f1809f4cce1cb76f35fa95ba6b716e99 (MD5) / Made available in DSpace on 2016-01-25T17:43:32Z (GMT). No. of bitstreams: 1 charlesdiasdebrito.pdf: 2413607 bytes, checksum: f1809f4cce1cb76f35fa95ba6b716e99 (MD5) Previous issue date: 2015-02-24 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Neste presente trabalho foi realizado uma busca conformacional dos ácidos graxos esteárico, oleico, palmítico, do álcool glicerol e do triacilglicerol (TAG) que é formado pela junção dos três ácidos citados anteriormente com o glicerol. Tais compostos estão todos situados na gordura do leite bovino [1]. Este foi o maior motivo para os tê-los estudados. Para isso, utilizamos a mecânica molecular (MM), dinâmica molecular (DM) e mecânica quântica (MQ). Foram feitas as otimizações destas moléculas no vácuo e na água. Então, após tais otimizações obtemos seus espectros infravermelho (IR) e RAMAN. Com os resultados obtidos fomos capazes de compará-los aos já existentes na literatura. Podendo estes resultados também, contribuir com informações de propriedades ópticas da gordura do leite bovino a grupos experimentais. Visto que conseguimos um resultado bastante detalhado e satisfatório. / In this present study was performed a conformational search of stearic fatty acids, oleic, palmitic, alcohol glycerol and the triacylglycerol (TAG) that is formed by the junction of the three acids above with glycerol. Such compounds are all situated in bovine milk fat. And this was the biggest reason to have them studied. For this, we use molecular mechanics ( MM ) , molecular dynamics (MD ) and quantum mechanics (QM ). Were made optimizations of these molecules in vacuum and water and then after such optimizations we obtain its infrared (IR) spectra and RAMAN. With the results we were able to compare them with existing in the literature.These results may also, contribute with information of optical properties of bovine milk fat the experimental groups. Since we can a very detailed and satisfactory result.

Indiana University-Purdue University Indianapolis (IUPUI) / Many cancers, including breast cancer, often develop resistance to chemotherapeutic drugs over a course of treatment. Many factors, including ABC transporter-mediated drug efflux, have been shown to play a role in acquired drug resistance. Fatty acid synthase (FASN), the key enzyme of lipid synthesis pathway, was found to be over-produced in an Adiamycin resistant breast cancer cell line MCF7/AdrVp3000, compared to its parental drug sensitive MCF7 cell line. Inhibition of FASN expression increased the drug sensitivity in breast cancer cells (MCF7/AdrVp3000 and MDA-MB-468), but not in the normal breast epithelia cell line MCF10A1. Enforced overexpression of FASN in MCF7 breast cancer cells decreased its drug sensitivity. These results indicated that FASN overexpression can induce drug resistance in breast cancers. Ectopic overexpression of FASN in MCF7 cells did not affect cell membrane permeability, transporter activity, nor did it affect cell proliferation rate. However, FASN overexpression protects cancer cells from drug-induced apoptosis by decreasing caspase-8 activation. In FASN over-expressing MCF7 cells, I discovered the positive feedback relationship between FASN and activation of Akt as previously reported. However, activation of Akt did not mediate FASN-induced drug resistance. Together with the findings that FASN expression associates with poor prognosis in several types of cancers, my investigations suggest that FASN overexpression is a novel mechanism of drug resistance in breast cancer chemotherapy. Inhibitors of FASN can be used as sensitizing agents in breast cancer chemotherapy.

No / RATIONALE: The carbon isotopic characterisation of ruminant lipids associated with ceramic vessels has been crucial for elucidating the origins and changing nature of pastoral economies. delta(13)C values of fatty acids extracted from potsherds are commonly compared with those from the dairy and carcass fats of modern domesticated animals to determine vessel use. However, the processing of wild ruminant products in pottery, such as deer, is rarely considered despite the presence of several different species on many prehistoric sites. To address this issue, the carbon isotope range of fatty acids from a number of red deer (Cervus elaphus) tissues, a species commonly encountered in the European archaeological record, was investigated. METHODS: Lipids were extracted from 10 modern red deer tissues obtained from the Slowinski National Park (Poland). Fatty acids were fractionated, methylated and analysed by gas chromatography/combustion/isotope ratio mass spectrometry (GCCIRMS). The delta(13)C values of n-octadecanoic acid and n-hexadecanoic acid, and the difference between these values (Delta(13)C), were compared with those from previously published ruminant fats. RESULTS: Nine of the ten deer carcass fats measured have Delta(13)C values of less than -3.3 per thousand, the threshold previously used for classifying dairy products. Despite considerable overlap, dairy fats from domesticated ruminants with Delta(13)C values less than -4.3 per thousand are still distinguishable. CONCLUSIONS: The finding has implications for evaluating pottery use and early pastoralism. The processing of deer tissues and our revised criteria should be considered, especially where there is other archaeological evidence for their consumption.

Les stérosomes, des vésicules artificielles composées d’amphiphiles monoalkylés et d’un grand pourcentage de stérols, sont prometteurs dans plusieurs domaines comme les industries pharmaceutiques et alimentaires. Il existe des stérosomes chargés négativement, positivement et neutres. Dans ce mémoire, nous avons approfondi nos connaissances sur les propriétés physico-chimiques des stérosomes chargés : acide palmitique (PA)/stérol et stéarylamine (SA)/cholestérol (Chol). Premièrement, afin de mesurer la diffusion latérale de PA dans les membranes PA/stérol (30/70 mol/mol) par RMN à gradients pulsés, nous avons tenté de former des bicouches liquide-ordonnées (lo) orientées magnétiquement avec ce mélange. En s'inspirant de l’idée que l’ajout de 1,2-dihexanoyl-sn-glycéro-3-phosphocholine (DHPC), un lipide à courtes chaînes, dans le système 1,2-dimyristoyl-sn-glycéro-3-phosphocholine (DMPC) mène à la formation de bicouches orientées, nous avons étudié la formulation PA perdeutéré/acide hexanoïque (HA)/Chol avec une proportion molaire de 25/18/57 à plusieurs températures; aucune formation de bicouches orientées n’a été observée. Ce résultat pourrait être expliqué par la solubilisation partielle de HA en milieu aqueux. Alors, une quantité insuffisante serait insérée dans la bicouche pour induire son orientation. La formulation PA perdeutéré/DHPC/Chol n’a pas conduit, elle non plus, à des bicouches orientées magnétiquement à des températures et concentrations lipidiques variées. En étudiant le mélange DMPC/DHPC/Chol (67/17/14), nous avons remarqué que la présence de Chol inhibait l'orientation magnétique des bicouches. Tandis que le mélange DMPC/DHPC/stigmastérol (SS) avec les proportions molaires 67/19/14 et 72/21/7 conduisait à des bicouches orientées avec leur normale (n) perpendiculaire au champ magnétique à 40 °C et 50 °C. Ces résultats suggèrent que le mélange PA/SS avec une proportion de lipide à courtes chaînes, HA et DHPC, pourrait mener à des bicouches orientées magnétiquement. Le mélange PA/Chol avec un lipide à courtes chaînes pourrait aussi être étudié en présence des lanthanides. Deuxièmement, nous avons examiné la possibilité de moduler la libération de matériel encapsulé dans des liposomes essentiellement composés de PA et d’un stérol. Il est connu que le mélange PA/Chol (30/70) à pH ≥ 7,5 forme des liposomes très peu perméables. Il est avantageux de pouvoir moduler la perméabilité pour avoir un contrôle sur le temps de libération de leur contenu, qui est un paramètre de grande importance pour les formulations liposomales de médicaments. D’abord, il a été montré que l’acide oléique (OA)/Chol (30/70) est capable de former des vésicules, ce qui n’avait jamais été prouvé auparavant. Par contre, les bicouches OA/Chol (30/70) ne sont pas plus perméables que les bicouches PA/Chol (30/70). L’ajout de 1-palmitoyl-2-oléoyl-sn-glycéro-3-phosphatidylcholine (POPC) dans le mélange PA/Chol n’augmente pas plus la perméabilité. En effet, les cinétiques de relargage de calcéine des vésicules PA/POPC/Chol (15/27.5/57.5), POPC/Chol (40/60) et POPC étaient très semblables à celle de PA/Chol (30/70). Il a été remarqué que les études littéraires se contredisent à propos de la perméabilité à la calcéine des bicouches de phosphatidylcholine (PC). L’explication de ces divergences est inconnue pour le moment. En remplaçant la moitié de la proportion molaire de Chol par le cholate de sodium (SC) dans le mélange PA/Chol (30/70), la membrane n’était pas plus apte à libérer son contenu. Il se pourrait que le SC se retrouvant dans la bicouche n’induit pas une diminution d’empilement. Il est aussi possible que le SC ne s'insère pas dans la membrane à cause de son hydrophilie considérable et il pourrait alors former seul des micelles. En remplaçant complètement le Chol par le sulfate de cholestérol (SChol), un stérol chargé négativement, et en préparant les vésicules à un bas pH, la formulation PA/SChol (30/70) mène à une très grande perméabilité à pH 7.5; le relargage est provoqué par un saut de pH. Nos travaux suggèrent qu'il serait possible de moduler la perméabilité des liposomes en les préparant avec le mélange PA/SChol/Chol en variant les proportions entre 30/63/7 à 30/70/0. Le diagramme pH-composition du mélange PA/SChol/Chol indique que ces proportions conduisent, à pH 7.4, à la coexistence de phases solide et lo en différentes proportions, ce qui pourrait moduler la perméabilité membranaire. Troisièmement, les résultats de perméabilité obtenus avec la calcéine et les difficultés survenues lors de l’extrusion des vésicules encapsulant cette sonde nous ont amené à nous demander si la calcéine interagit avec les bicouches chargées. L’impact de certains anions, dont la calcéine, a été examiné sur les bicouches chargées positivement SA/Chol (50/50). La calorimétrie différentielle à balayage (DSC, de l’anglais differential scanning calorimetry), indique qu’il n’y a aucune transition entre 25 et 90 °C pour les liposomes SA/Chol (50/50) à pH = 7.4. L’ajout de chlorure de sodim (375 mM) n’a pas mené à la formation d’agrégats et aucune transition n’a été observée sur le thermogramme. La formation d’agrégats macroscopiques instantanément après l’ajout d’hydrogénophosphate de sodium (125 mM), de sulfate de sodium (125 mM) et de calcéine (3 mM) a été observée. Une transition a été observée sur les thermogrammes en présence de ces sels. Les agrégats observés pourraient être associés à la transition de phase. L’effet des anions sur la température et l’enthalpie de transition suivent le même ordre que la série d’Hofmeister : sulfate > hydrogénophosphate > chlorure (pas de pic). La calcéine avait l’impact le plus prononcé sur l’agrégation; ceci illustre que la calcéine n’est pas une sonde fluorescente inerte avec le mélange SA/Chol. Elle pourrait être un chaotrope volumineux. De plus, les interactions SA-calcéine plus fortes, menant à l’agrégation des vésicules, que les interactions PC-calcéine pourraient s’expliquer par le fait que la SA est chargée positivement. / Sterosomes are artificial vesicles that are composed of monoalkylated amphiphiles and a large percentage of sterols. They are promising in areas such as pharmaceutical and food industries. Sterosomes can be found in anionic, cationic and neutral form. The work of this master’s thesis focuses on gaining additional knowledge on the physicochemical properties of charged sterosomes such as palmitic acid (PA)/sterol and stearlyamine (SA)/cholesterol (Chol). Our first aim was to find an approach to form liquid-ordered (lo) bilayers that can orient in a magnetic field with the PA/sterol (30/70 mol/mol) mixture. This will allow us to study the lateral diffusion of PA. It has been demonstrated that mixing 1,2-diheptanoyl-sn-glycero-3-phosphocholine (DHPC), a short chain lipid, with 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) results in bilayers that orient with their normal (n) perpendicular to the magnetic field. Therefore, perdeuterated PA/hexanoic acid (HA)/Chol (25/18/57) mixture was studied at different temperatures; however, results showed no bilayer orientation. It was suggested that this could be due to the partial solubility of HA in aqueous phase. Consequently, an insufficient quantity of HA was available to induce bilayer orientation. Furthermore, perdeuterated PA/DHPC/Chol mixture was studied at different temperatures and lipid concentrations, which also led to no bilayer orientation. While studying DMPC/DHPC/Chol (67/17/14) formulation, it was understood that Chol inhibits bilayer orientation. On the other hand, two different molar proportions of DMPC/DHPC/stigmasterol (SS) (67/19/14 and 72/21/7) led to bilayers that orient with their n perpendicular to the magnetic field at 40 °C et 50 °C. These results suggest that by adding a short chain lipid such as HA and DHPC to PA/SS mixture could lead to oriented bilayers. Another interesting track would be to work with PA/short chain lipid/Chol mixture in the presence of lanthanides. Our second aim was to find different formulations of vesicles, containing at least PA and a sterol, with distinctive permeability. It has already been established that PA/Chol (30/70) bilayers are in lo phase as long as PA is deprotonated (pH ≥ 7,5) and have a very limited permeability. The ability to modulate permeability would allow control over the release time of an encapsulated product, which is an important parameter in the development of novel liposomal drug delivery systems. It was proven that oleic acid (OA)/Chol (30/70) mixture is able to form bilayers, which has not been shown previously. However, OA/Chol (30/70) bilayers were not much more permeable than PA/Chol (30/70) bilayers. Adding 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) in PA/Chol system did not lead to higher permeability either. Results of calcein release kinetics from PA/POPC/Chol (15/27.5/57.5), POPC/Chol (40/60) and POPC vesicles were not very different from the one found for PA/Chol (30/70) vesicles. It was noted that contradictory results were found in the literature regarding calcein permeability from phosphatidylcholine (PC) membranes. For the moment, explanations related to these divergences have yet to be given. Furthermore, no increase in membrane permeability was found after substituting half of the molar proportion of Chol by sodium cholate (SC) in PA/Chol (30/70) mixture. One suggestion would be that SC insertion in the bilayer does not induce a reduction in the packing of lipids. Another suggestion would be that SC does not insert in PA/Chol bilayers due to its considerable hydrophilic character and forms micelles on its own. Highly permeable membrane was found when Chol was completely replaced by cholesterol sulfate (SChol), a negatively charged sterol, and vesicle preparation was done at low pH. The pH-triggered release method was used. Our work suggests that by varying the molar proportion of PA/SChol/Chol mixture between 30/63/7 and 30/70/0, it would be possible to obtain different vesicle formulations with distinctive permeability. In between these molar proportions, the pH-composition diagram of PA/SChol/Chol shows the coexistence of solid and lo phases in different proportions at pH 7.4, which could modulate the permeability. Some ambiguous calcein release results and struggles arising from the extrusion of calcein-encapsulated liposomes led us to wonder if this dye interacts with charged bilayers. The impact of some anions, including calcein, was examined on SA/Chol (50/50) charged bilayers. Thermodynamic studies were done by differential scanning calorimetry (DSC). SA/Chol (50/50) mixture showed no transition between 25 and 90 °C at pH 7.4. In the presence of sodium chloride (375 mM), there was no indication of aggregation or the appearance of a transition on the thermogram. Macroscopic aggregates were instantly observed after addition sodium hydrogenphosphate (125 mM), sodium sulphate (125 mM) and calcein (3 mM). Furthermore, a phase transition was also noticed on the thermograms in the presence of these salts. It is suggested that the appearance of the transition can be associated with the formation of aggregates. The effect of anions on the transition temperature and enthalpy follows the Hofmeister series: sulfate > hydrogenphosphate > chloride (no peak). Calcein had the highest impact on the formation of aggregates. This indicates that calcein is not a good candidate to be used as a fluorescent dye with SA/Chol mixture. It was suggested that calcein could be a large chaotrope anion. In contrast to PC-calcein interactions, SA-calcein interactions led to the aggregation of vesicles probably due to stronger interactions in the presence of positively charged SA.

No description available.

No description available.

Made available in DSpace on 2017-07-10T18:13:24Z (GMT). No. of bitstreams: 1 Leticia Hayashi Higuchi.pdf: 582942 bytes, checksum: ca2772e3dba8283759f014b96b1057e9 (MD5) Previous issue date: 2010-07-09 / The aim of this study was evaluate the inclusion of different vegetable oils obtained by mechanical extraction in the feeding of Nile tilapia (Orechromis niloticus). The first study evaluate the performance and hundredth composition of Nile tilapia were aimed. We conducted the experiment at the Laboratory Cultivation of Aquatic Organisms from Research Group GEMAq/Unioeste with 320 Nile tilapia with initial weight and initial medium total length of 2.55 ± 0.57 g and 5.59 ± 0.43 cm, respectively. The treatments included oils of (sunflower, canola, sesame, linseed, peanut, nut of Pará, soy and macadamia nuts) with an addition of 4%, with diets containing 32% crude protein and 3500 kcal/kg energy digestible. Was valued the weight gain (GP), total length (CT), feed conversion apparent (CAA), diet consumption (CR) and survival (SO). There was no significant difference (P> 0.05) between the performance variables. However, distinctions can be observed (P <0.05) on water content, crude protein and total lipid to the hundredth composition after 30 and 60 days of experiment. In the second study, the objective was to evaluate the quantification on fatty acids in lipids of tilapia fingerlings. The major fatty acids (mg/g total lipids (LT)) were oleic, palmitic, linoleic and linolenic. The sum of fatty acids polyunsaturated after 60 days of culture showed an increase in all treatments compared with 30 days of experiment. This is due to the addition of oils with high contents of fatty acids n-6 and n-3 in the diet. In conclusion it is recommended to use linseed oil as feed for tilapia fingerlings, due to the great improvement in the ratio of n-6/n-3. / O objetivo desse experimento foi avaliar a inclusão de diferentes óleos vegetais obtidos por extração mecânica na alimentação de tilápias do Nilo (Orechromis niloticus). O primeiro estudo objetivou avaliar o desempenho e a composição centesimal de tilápias do Nilo. Realizou-se o experimento no Laboratório de Cultivo de Organismos Aquáticos do Grupo de Pesquisa GEMAq/Unioeste com 320 tilápias do Nilo com peso inicial e comprimento total inicial médio de 2,55 ± 0,57 g e 5,59 ± 0,43 cm, respectivamente. Os tratamentos contaram com a inclusão dos óleos de (girassol, canola, gergelim, linhaça, amendoim, castanha do Pará, soja e macadâmia) com uma inclusão de 4%, com rações contendo 32% de proteína bruta e 3500 kcal/kg de energia digestível. Foram avaliadas as médias de ganho de peso (GP), comprimento total (CT), conversão alimentar aparente (CAA), consumo de ração (CR) e sobrevivência (SO). Não houve diferença significativa (P>0,05) entre as variáveis de desempenho. No entanto, pode-se observar distinções (P<0,05) nos teores de umidade, proteína bruta e lipídeos totais para a composição centesimal após os 30 e 60 dias de experimento. No segundo estudo, o objetivo foi avaliar a quantificação dos ácidos graxos nos lipídios totais de alevinos de tilápias. Os ácidos graxos majoritários (mg/g de lipídeos totais (LT)) foram oléico, palmítico, linolênico e linoléico. As somatórias dos ácidos graxos poliinsaturados aos 60 dias de cultivo apresentaram aumento em todos os tratamentos em comparação aos 30 dias de experimento. Isto se deve a adição dos óleos com altos conteúdos de ácidos graxos n-6 e n-3 nas rações. Como conclusão recomenda-se o uso do óleo de linhaça na alimentação de alevinos de tilápias, devido à grande melhoria na relação entre n-6/n-3.

Indiana University-Purdue University Indianapolis (IUPUI) / Cellular membranes contain a staggering diversity of lipids. The lipids are heterogeneously distr ibuted to create regions, or domains, whose physical properties differ from the bulk membrane and play an essential role in modulating the function of resident proteins. Many basic questions pertaining to the formation of these lateral assemblies remain. T his research employs model membranes of well - defined composition to focus on the potential role of polyunsaturated fatty acids (PUFAs) and their interaction with cholesterol (chol) in restructuring the membrane environment. Omega - 3 (n - 3) PUFAs are the main bioactive components of fish oil, whose consumption alleviates a variety of health problems by a molecular mechanism that is unclear. We hypothesize that the incorporation of PUFAs into membrane lipids and the effect they have on molecular organization may be, in part, responsible. Chol is a major constituent in the plasma membrane of mammals. It determines the arrangement and collective properties of neighboring lipids, driving the formation of domains via differential affinity for different lipids . T he m olecular organization of 1 -[ 2 H 31 ]palmitoyl -2- eicosapentaenoylphosphatidylcholine (PEPC - d 31 ) and 1 -[ 2 H 31 ]palmitoyl -2- docosahexaenoylphosphatidylcholine (PDPC -d 31 ) in membran es with sphingomyelin (SM) and chol (1:1:1 mol) was compared by solid - state 2 H NMR spectroscopy. Eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids are the two major n - 3 PUFAs found in fish oil, while PEPC -d 31 and PDPC -d 31 are phospholipids containing the respective PUFAs at the sn - 2 position and a perdeuterated palmitic acid a t the sn - 1 position . Analysis of s pectra recorded as a function of temperature indicate s that in both cases, formation of PUFA - rich (less ordered) and SM - rich (more ordered) domains occurred. A surprisingly substantial proportion of PUFA was found to infil trate the more ordered domain. There was almost twice as much DHA (65%) as EPA (30%) . The implication is that n - 3 PUFA s can incorporate into lipid rafts, which are domains enriched in SM and chol in the plasma membrane, and potentially disrupt the activity of signaling proteins that reside therein. DHA, furthermore, may be the more potent component of fish oil. PUFA - chol interactions were also examined through affinity measurements. A novel method utilizing electron paramagnetic resonance (EPR) was develope d, to monitor the partitioning of a spin - labeled analog of chol , 3β - doxyl - 5α - cholestane (chlstn), between large unilamellar vesicles (LUVs) and met hyl - β - cyclodextrin (mβCD). The EPR spectra for chlstn in the two environments are distinguishable due to the substantial differences in tumbling rates , allowing the population distribution ratio to be determined by spectral simulation. Advantages of this approach include speed of implementation and a vo idance of potential artifact s associated with physical separation of LUV and mβCD . Additionally, in a check of the method, t he relative partition coefficients between lipids measured for the spin label analog agree with values obtained for chol by isothermal titration calorimetry (ITC). Results from LUV with different composition confirmed a hierarchy of decreased sterol affinity for phospholipids with increasing acyl chain unsaturation , PDPC possessing half the affinity of the corresponding monounsaturated phospholipid. Taken together, the results of these studies on model membranes demonstrate the potential for PUFA - driven alteration of the architecture of biomembranes, a mechanism through which human health may be impacted.

No description available.