Bilayer lipid membranes (BLMs) are formed from phospholipid molecules which self-assemble into a lipid bilayer with 4 to 9 nm thickness when submerged in an aqueous solution. This is due to their amphiphilic nature, meaning that one part of the molecule is hydrophilic, or attracted to water, and one part is hydrophobic, or repelled by water. They are the primary structural component of cell membranes in living organisms and therefore are useful for modeling the properties of cell membranes since they share many of the same chemical and physical properties. The objective of this dissertation is to investigate the maximum pressure that can be withstood by a BLM formed over a porous substrate, which will be referred to as the failure pressure. This work represents the first time that this quantity has been measured and reported. The failure pressure is investigated in several complementary ways, including mechanical, electrical, and optical measurements and modeling. The phospholipids that are tested include 1-Stearoyl-2-Oleoyl-sn-Glycero-3-Phosphatidylcholine (SOPC) and mixtures of SOPC and cholesterol (CHOL), which was chosen because cholesterol is known to increase the strength of SOPC BLMs. A new test methodology was developed to measure the failure pressure of BLMs. A custom test fixture was used to pressurize BLMs while measuring the applied pressure with a high degree of precision and repeatability. The BLMs were tested in an electrolyte solution over substrates that contained a single pore and also substrates that contained an array of many pores. SOPC BLMs were tested over single pore substrates with pore sizes ranging from 5 to 20 microns, and this resulted in failure pressures from 67 to 19 kPa, respectively. For single pore tests, the addition of 50 mol% cholesterol to SOPC resulted in a 56% higher failure pressure on average than SOPC alone. For multi pore substrates, SOPC BLMs were tested using pore sizes between 0.05 and 10 microns, which yielded bulk failure pressures of 380 to 1.5 kPa, respectively. For multi pore tests, SOPC/CHOL-50 mol% resulted in a 47% higher bulk failure pressure on average. A model was developed to predict the pressurization curve of BLMs and was applied to both the single and multi pore tests. It was found that the failure pressure of BLMs follows a distribution which was well modeled by a Weibull distribution with a positive skew. Parameters such as the Weibull shape parameter were determined by fitting the model to the experimental pressurization curves and it was found that the shape of the Weibull distribution was nearly the same for every pore size. Using the pressurization model it was estimated that the percentage of failed BLMs that were pressurized over a multi pore substrate ranged from 4% to 33%. The model also coupled the bulk failure pressure of BLMs formed over multiple pores to the failure pressure of a single BLM, showing that the bulk failure pressure of multiple BLMs is smaller than the failure pressure of a single BLM because it represents the failure of only the weakest BLMs in a group. Electrical impedance was measured before and after pressurization of the BLMs, and these measurements were modeled by assuming that the BLMs act as a resistor and a capacitor configured in parallel. In general, the impedance magnitude dropped by two to three orders of magnitude after BLM pressurization, which was a result BLMs failing and opening conductive pathways through the subsequently empty pores. It was found that normalized conductance values for SOPC BLMs were between G / A = 4 x 10^-12 and 2 x 10^-8 S/cm^2, and normalized capacitance values varied between C / A = 3 x 10^-14 and 1 x 10^-10 F/cm^2. In the literature these values ranged from G / A = 10^-1 to 10^-9 S/cm^2 and C / A = 10^-6 to 10^-8 F/cm^2, having a wide range of values due to the many variations of experimental test procedures. Visual images of BLMs were produced using fluorescence microscopy. Images were recorded before and after pressurization of SOPC BLMs formed over a multi pore substrate. As predicted by the pressurization model, it was found that some but not all BLMs fail after pressurization. It was also found that BLMs fail over the center of a pore, and leave remnants around the perimeter of the pore. / Ph. D.

Gas chromatography (GC) and gas chromatography olfactometry (GCO) was used to determine the effect of specific light wavelengths on light oxidation in milk. The most damaging wavelengths to milk quality appear to be the UV (200-400 and 395 nm) and short visible (463 nm) wavelengths. However, exposure to 610 nm also appears to be damaging. GC and GCO were also used to look at the efficacy of film over-wraps made from iridescent films. Single-layer over-wraps were not as effective in reducing light oxidation as multi-layer film over-wraps. Single-layer over-wrap treatments had higher numbers of odor-active compounds than multi-layer over-wrap treatments with a number of odor-active compounds detected consistently in single-layer over-wrap treatments but not in the multi-layer over-wrap treatments. Concentrations of volatile compounds were slightly lower in the multilayer treatments. Multi-layer film over-wrap treatments were tested for light oxidation flavor intensity with a balanced incomplete block multi-sample difference test using a ranking system and a trained panel. Packaging over-wraps limited the production of light oxidation flavor in milk over time but not to the same degree as the complete light block. Blocking all visible riboflavin excitation wavelengths was better at reducing light oxidation flavor than blocking only a single visible excitation wavelength. A method to determine light oxidation in oil using Fourier Transform Infrared (FTIR) spectroscopy was established and preliminary data is presented. / Ph. D.

High lipid : low dextrose (HL:LD) parenteral admixture (PA) is high in polyunsaturated fatty acids (PUFA) that are sensitive to peroxidation. This study evaluated the antioxidative effect of vitamin E in both HL:LD PA and in obese cats given HL:LD PA. Natural d-α-tocopherol (Vital E-300) was added to HL:LD PA at seven concentrations (8, 12, 16, 24, 32, 48, or 64 IU/g of lipid). PA were exposed to fluorescent light for 24 hours at room temperature. Hydroperoxides were measured at baseline and 24 hours hang time. Significantly lower hydroperoxide concentrations were found with > 24 IU/g of lipid at baseline (P < 0.01). A higher d-α-tocopherol concentration was required (> 48 IU/g lipid) to lower hydroperoxides at 24 hours (P < 0.0001). HL:LD PA with 40 IU/g lipid/day d-α-tocopherol was delivered intravenously to obese cats (PA Toc⁺) over 48 hours. Control cats (PA Toc⁻) received HL:LD PA without a d-α-tocopherol supplementation. Oxidative status of cats was evaluated at baseline and 24, 48, and 96 hours. Cats in both groups exhibited an increase in MDA concentration (time effect; P < 0.0001). WBC-tGSH and WBC-GPx did not change in either group of cats. RBC-tGSH and RBC-GPx changed over time (time effects; P = 0.0005; P = 0.0016, respectively) with the PA Toc⁺ cats exhibiting a higher RBC-tGSH concentration (treatment x time interaction; P = 0.012). Serum α- and γ-tocopherol concentrations increased in PA Toc⁺ cats (treatment effect; P < 0.0001). These findings suggest that d-α-tocopherol significantly alters oxidative status in vivo. / Master of Science

The Hulver laboratory has recently found that the neuropeptide Y Y1 receptor (NPY Y1R) mRNA expression is elevated in skeletal muscle of obese humans (Hulver, unpublished). The goal of this research is to study the role of the NPY Y1R in skeletal muscle lipid metabolism. Rat L6, mouse C2C12, and human primary myotubes were incubated in 14C palmitate labeled fatty acid oxidation medium containing 80ng/mL, 250ng/mL, and 500ng/mL of NPY and for a three hour period. Experiments were repeated with the addition of 17mg/mL diprotin A to each NPY treatment. Fatty acid oxidation (FAO) and the percentage of lipids stored within the myotubes as diacylglyceride (DAG) and triaclyglyceride (TAG) were measured. Analyses were repeated in rat L6 and mouse C2C12 following a three hour incubation in 14C palmitate labeled fatty acid oxidation medium containing 1µg/mL, 10µg/mL, and 50µg/mL of the NPY Y1R ligand, [Leu31, Pro34] neuropeptide Y (Bachem, Torrance, CA). Incubation of human primary myotubes in NPY treatments with the addition of diprotin A significantly increased TAG accumulation (p< 0.05). Mouse C2C12 mytoube incubation in 500ng/mL NPY with diprotin A increased FAO (p 0.05). All other NPY and NPY Y1R ligand treatments in had no significant effect on FAO or the accumulation of TAG and DAG. / Master of Science

Yes / The removal or structural disruption of crystallised lipid is a pivotal but energy-intensive step in a wide range of industrial and biological processes. Strategies to disrupt the structure of crystallised lipid in aqueous solution at lower temperatures are much needed, where nanoparticle-based strategies show enormous promise. Using the aqueous tristearin bilayer as a model for crystallised lipid, we demonstrate that the synergistic use of surfactant and detonation nanodiamonds can depress the onset temperature at which disruption of the crystallised lipid structure occurs. Our simulations reveal the molecular-scale mechanisms by which this disruption takes place, indicating that the nanodiamonds serve a dual purpose. First, the nanodiamonds are predicted to facilitate delivery of surfactant to the lipid/water interface, and second, nanodiamond adsorption acts to roughen the lipid/water interface, enhancing ingress of surfactant into the bilayer. We find the balance of the hydrophobic surface area of the nanodiamond and the nanodiamond surface charge density to be a key determinant of the effectiveness of using nanodiamonds to facilitate lipid disruption. For the nanodiamond size considered here, we identify a moderate surface charge density, that ensures the nanodiamonds are neither too hydrophobic nor too hydrophilic, to be optimal.

Replacing fossil fuels with algae, a renewable resource, is an exciting possibility. This study evaluates the algae found in South Texas brackish water ponds used for aquaculture of fish as a possible source of biofuels. Samples of algae from these ponds were cultured at varying temperatures ranging from 15.5ºC to 36.5ºC. High levels of growth were observed at 20.5ºC and the highest lipid content was measured at 23.0ºC. Temperature was also a factor in the distribution of microalgal taxa throughout the temperature gradient. This information will be added to the growing body of research investigating similar cultures of algae for future biofuel production. / text

The temperature-dependent catalytic activity of rat liver 3-hydroxy-3 -methylglutaryl coenzyme A reductase (HMG-CoA reductase) displays the nonlinear Arrhenius behavior characteristic of many membrane-bound enzymes. A two-conformer equilibrium model has been developed to characterize this behavior. In the model, HMG-CoA reductase undergoes a conformational change from a low specific activity to a high specific activity form. This conformation change is apparently driven by a temperature-dependent phase transition of the membrane lipids. It has been found that this model accurately describes the data from diets including rat chow, low-fat, high-carbohydrate, and diets supplemented with fat, cholesterol or cholestyramine. The effects characterized by the model are consistent with the regulation of HMG-CoA reductase by enzyme-lipid interactions.

Os mastócitos são células multifuncionais do sistema imunológico que participam em diversos processos biológicos. As funções dos mastócitos estão diretamente relacionados com a sua ativação e, subsequente, liberação de mediadores químicos. Os eventos iniciais da ativação dos mastócitos e da transdução de sinais ocorrem em microdomínios lipídicos (lipid rafts) da membrana plasmática. Os gangliosídeos derivados do GD1b são constituintes dos lipid rafts de mastócitos de roedores. O intercruzamento destes gangliosídeos pelo mAb AA4, resulta na formação de agregados (caps) na superfície celular e promove uma ativação parcial dos mastócitos, sem que ocorra a desgranulação. A ativação é semelhante a observada quando os FcRIs são intercruzados por antígenos multivalentes ligados a IgEs, mas neste caso ocorre a desgranulação. O presente estudo tem como objetivo caracterizar o papel dos gangliosídeos derivados do GD1b na liberação de mediadores de mastócitos da linhagem RBL-2H3. O intercruzamento dos gangliosídeos derivados do GD1b resulta na ativação dos fatores de transcrição NFAT e NFB e esta ativação é mediada pela proteína quinase Syk. A ativação destes fatores de transcrição resulta na liberação de mediadores neo-sintetizados, tais como: TNF-, interleucina (IL)-4. Por outro lado, o intercruzamento dos gangliosídeos derivados de GD1b não induz a liberação dos mediadores neoformados como o leucotrieno B4 (LTB4) e o leucotrieno C4 (LTC4). A agregação dos gangliosídeos derivados do GD1b resulta na desorganização dos lipid rafts e na redistribuição de seus componentes, como demostrado pela análise proteômica. Estes dados mostraram proteínas capazes de desencadear uma ativação parcial dos mastócitos e proteínas reguladoras negativas da desgranulação estão up reguladas, enquanto que proteínas críticas para a transdução do sinal estão down reguladas. Os resultados obtidos neste trabalho demonstram que os gangliosídeos derivados do GD1b desempenham papel crucial na integridade dos lipid rafts modulando a ativação e liberação de mediadores de mastócitos. / Mast cells are immunoregulatory cells that participate in diverse biological events. The action of mast cells is directly related to their activation and subsequent mediator release. Early signal transduction events occur in lipid rafts in the plasma membrane. GD1b-derived gangliosides are known constituents of lipid rafts in rodent mast cells. The cross-linking of these gangliosides by mAb AA4 results in a partial activation of mast cells similar to that observed when FcRIs are cross-linked, but does not result in the mast cell degranulation. With time, the gangliosides bound to mAb AA4 cap on the cell surface. The present study aims to characterize the role of the rodent mast cell specific gangliosides derived from GD1b in mediator release from RBL-2H3 mast cells. Cross-linking the GD1b-derived gangliosides activated the transcription factors NFAT and NFB and this activation was mediated by Syk. The activation of theses transcription factors by cross-linked GD1b-derived gangliosides results in the release of the neo-synthesized mediators TNF- and interleukin (IL)-4. However, cross-linking GD1b-derived gangliosides did not stimulate release of the newly formed mediators leukotriene B4 (LTB4) and leukotriene C4 (LTC4). Capping of GD1b-derived gangliosides disorganized lipid rafts and resulted in a redistribution of lipid raft components. Proteomic analysis showed that proteins that trigger mast cell activation and negative regulatory proteins of degranulation are up regulated, whereas proteins critical for signal transduction are down regulated in mast cells where the gangliosides are capped. The results of this work demonstrate that the mast cell-specific GD1b-derived gangliosides are crucial in maintaining the functional integrity of the lipid rafts and modulate cell activation and subsequent mediator release from mast cells.

Para se verificar o efeito de drogas hipolipemizantes sobre a qualidade do ovo, desempenho das aves, níveis de Iípides plasmáticos e colesterol na gema do ovo, foram realizados dois experimentos utilizando-se galinhas poedeiras Shaver. No experimento 1, 240 aves com 30 semanas de idade, foram alimentadas durante 12 semanas com dieta comercial (CON1) acrescida de Probucol a 0,1% (PROB), Gemfibrozil a 0,025% (GEMF) e Lovastatina em três concentrações: 0,0005% (LOV1), 0,001% (LOV2) e 0,0015% (LOV3), totalizando seis tratamentos. No experimento 2, 128 aves com 26 semanas de idade, receberam como alimentação, durante seis semanas, dieta formulada sem ingredientes de origem animal (CON2), acrescida de Colestiramina a 0,2% (COL 1) e 0,3% (COL2) e Lovastatina a 0,005% (LOV4), perfazendo um total de quatro tratamentos. Em ambos os experimentos, a adição das drogas não prejudicou a qualidade da casca e do albúmen dos ovos e, de um modo geral, não determinou efeitos indesejáveis sobre o desempenho produtivo das aves, com exceção da redução observada no peso médio dos ovos no experimento 2. No experimento 1, em relação aos lípides plasmáticos, a adição de drogas à ração determinou reduções de significado estatístico (p<0,05), nos triglicérides, apenas no LOV2 (38,5%), e no colesterol total, nos grupos LOV2 (36,0%), LOV3 (36,8%), PROB (29,6%) e GEMF (30,4%). Não foram consignadas alterações significativas nos níveis de HDL-colesterol em relação ao CON 1, observando-se, com exceção do GEMF, tendência a elevação de seus valores com o uso das diferentes drogas. Verificou-se redução significativa (p<0,05) do colesterol na gema (mg/g) nos grupos LOV1 (7,4%) e LOV3 (12,1%). No experimento 2, os lípides plasmáticos não sofreram alterações de significado estatístico em relação ao CON2, sendo que os triglicérides e o colesterol total mostraram tendência a diminuição no LOV4. A concentração de colesterol na gema (mg/g) permaneceu inalterada, em cotejo com o CON2, mediante a adição das drogas utilizadas no experimento 2. Os efeitos da Lovastatina sobre as concentrações de Iípides sanguíneos e de colesterol do ovo foram menos evidentes no experimento 2, onde as aves apresentavam níveis de Iípides plasmáticos mais reduzidos. Os coeficientes de correlação e as equações de regressão calculados mostraram que o peso da gema aumenta conforme o peso do ovo se eleva (p<0,05), e que um aumento do peso da gema corresponde a um incremento de seu teor de colesterol, indicando que as variações dos níveis de colesterol por gema podem ser, em parte, justificadas pelas diferenças entre os pesos dos ovos. / Two experiments were carried out to evaluate the effect of lipid¬lowering agents upon egg quality, reproductive performance, plasma lipids and egg yolk cholesterol levels of Shaver laying hens. In the first trial, two hundred and forty 30-week-old hens were fed basal diet (commercial ration - CON1) supplemented with 0.1 % Probucol (PROB), 0.025% Gemfibrozil (GEMF), or Lovastatin at 0.0005% (LOV1), 0.001 % (LOV2) and 0.015% (LOV3) for a 12-week experimental period. In experiment 2, one hundred and twenty-eight 26-week-old hens were fed basal diet without animal products (CON2) containing either 0.2% Cholestyramine (CaL 1), 0.3% Cholestyramine (COL2) or 0.005% Lovastatin (LOV4) for a period of six weeks. At the termination of both experiments, it was observed that the supplement of the drugs did not impair albumen and shell quality. In addition, hen performance was not adversely affected, with the exception of the significant reduction (p<0.05) in egg weights observed in experiment 2. In experiment 1, with regard to the plasma lipids, the depression in triglyceride concentrations approached statistical significance (p<0.05) only in LOV2 (38.5%), and total cholesterol was significantly depressed (p<0.05) in LOV2 (36.0%), LOV3 (36.8%), PROB (29.6%) and GEMF (30.4%) groups. HOL-cholesterol levels were not significantly altered by drug treatments; but with the exception of GEMF, there was a trend towards the elevation by the use of other drugs. Egg cholesterol content, expressed per gram of yolk was significantly lowered (p<0.05) in LOV1 (7.4%) and LOV3 (12.1 %). In experiment 2, no significant changes were observed on plasma lipids due to the addition of the drugs, but cholesterol and triglyceride levels tend to reduction in LOV4 group. Egg yolk cholesterol remained unchanged in experiment 2 with the supplement of the drugs. The effect of Lovastatin on plasma lipid and egg yolk cholesterol concentration was less remarkable in experiment 2, when hens presented lower plasma lipid levels. When correlation coefficients and regression equations were calculated, it was found that yolk weight increased linearly (p<0.05) as egg weight raised, and the higher the yolk weight, the higher the yolk cholesterol content, indicating that yolk cholesterol content changes may be partially explained by differences among egg weights.

A organização da membrana biológica em microdomínios tem um papel chave em vários processos celulares semelhante a receptores protéicos e a transdução de sinal. A existência de microdomínios, também denominados de rafts tem sido explicada pela separação das membranas lipídicas em duas fases: liquida cristalina (L) e fase liquida ordenada (Lo) rica em colesterol e esfingolipídeos. Assim, o enfoque deste projeto foi correlacionar mecanismos de controle da atividade da fosfatase alcalina (TNAP) com a organização intermolecular e o estado de fase de alguns lipídios que compõem as vesículas da matrix. Foi estudada a modulação da atividade da enzima e sua inserção à sistemas de lipossomos constituídos com diferentes composições lipídicas (Dipalmitoilfosfatidilcolina, Colesterol, Esfingomielina e Gangliosídeo) como um mecanismo de regulação e transdução entre enzimas que não compartilham intermediários metabólicos comuns. Isto é, verificar como mudanças de organização molecular, induzida por colesterol e/ou outros lipídios, podem modular a atividade de enzimas regulando a produção de mensageiros lipídicos secundários e/ou processos de fusão e recombinação topológica da bicamada lipídica, modulando concomitantemente a atividade da fosfatase alcalina. Com tal propósito, a TNAP foi reconstituída em lipossomos constituídos de DPPC e lipossomos mistos formando sistemas binários DPPC:Chol, DPPC:SM e DPPC:GM1 com razões molares de (9:1); sistemas terciários DPPC:Chol:SM, DPPC:Chol:GM1 e DPPC:SM:GM1 com razões molares de (8:1:1) e por fim sistemas quaternários constituídos de DPPC:Chol:SM:GM1 (7:1:1:1). Estes sistemas foram propostos com o intuito de mimetizarmos os lipid rafts existentes nas membranas biológicas, porém utilizando lipídios que já foram identificados e quantificados nas vesículas da matrix. Foram avaliados os efeitos da composição lipídica dos lipossomos na inserção da enzima aos sistemas vesiculares. Além disso, foram realizados estudos biofísicos de calorimetria analisando como os parâmetros termodinâmicos são afetados com as diferentes composições lipídicas e pela presença da enzima ancorada aos sistemas. A reconstituição da enzima a lipossomos constituídos de DPPC proporcionou uma incorporação em torno de 80% da atividade enzimática. Estudos termodinâmicos dos proteolipossomos formados evidenciaram uma queda significativa nos valores de variação de entalpia em relação aos sistemas de lipossomos (de 7,63 a 1,88 kcal.mol-1). Lipossomos binários constituídos de DPPC:Chol em concentrações crescentes (9:1, 9:2, 9:3, 7:3, 9:4 e 9:5 razão molar) foram estudados tanto pelos parâmetros biofísicos como pela habilidade de inserção da enzima a tais sistemas. Foi observado um significativo decréscimo nos valores de variação entalpia com o aumento da proporção de colesterol no lipossomo. Além disso, a presença do colesterol proporcionou uma redução na inserção da atividade catalítica em até 42%, quando utilizada a composição lipídica de 9:5 DPPC:Chol. Dos sistemas binários formados com razões molares 9:1, o que apresentou maior porcentagem de reconstituição da TNAP foi o sistemas DPPC:Chol, apresentando em torno de 62% de incorporação da enzima. Os sistemas terciários apresentaram ao redor de 30% de incorporação da atividade catalítica e o sistema quaternário em torno de 25%. Além dos ensaios de atividade enzimática, a incorporação da enzima aos sistemas vesiculares também pôde ser comprovada pelas mudanças nos parâmetros termodinâmicas detectados por DSC. Nos estudos de calorimetria de todos os sistemas de proteolipossomos formados, foram observadas significativas diminuições nos valores de variação de entalpia quando comparados aos sistemas de lipossomos correspondentes. Deste modo, os resultados aqui apresentados fornecem novas informações que poderão contribuir tanto para a compreensão do comportamento da atividade da fosfatase alcalina na presença de diferentes composições lipídicas dos microdomínios existente membrana, quanto para o entendimento dos processos de regulação da enzima durante o processo de biomineralização. / The organization of the biological membrane in microdomains has a key roll in many cellular processes similar to proteic receptors and signal transduction. The existence of microdomains, also called rafts, has been explained by the lipid membrane separation in two phases: crystalline phase (L) and ordinate liquid phase (Lo), rich in cholesterol and sphingolipids. The focus of this Project was to correlate activity control mechanisms of the alkaline phosphatase (TNAP) with the intermolecular organization and the phase stat of some lipids that comprise the matrix vesicles. The enzyme activity modulation and its insertion into liposomes systems, constituted by different lipid compositions (DPPC, Chol, SM e GM1) as a regulation and transduction mechanism between enzymes that do not share common intermediary metabolites, was studied. That is, to verify how molecular organization changes, induced by cholesterol and/or other lipids, can modulate the enzyme activity regulating the production of secondary lipid messengers and/or fusion processes and topological recombination of the lipidic bilayer, concomitantly modeling the alkaline phosphatase activity. TNAP was then reconstituted in liposomes constituted by DPPC and mixed liposomes forming binary systems DPPC:Chol , DPPC:SM , DPPC: Chol:GM1 with (9:1) molar rates; tertiary systems DPPC:Chol:SM, DPPC:Chol:GM1 and DPPC:SM:GM1 with (8:1:1) molar rates and finally quaternary system constituted by DPPC:Chol:SM:GM1 (7:1:1:1). These systems were proposed aiming the mimetization of lipid rafts existent in biological membranes, but using lipids that had already been identified and quantified in the matrix vesicles. The effects of liposome lipid composition in the enzyme insertion to the vesicular systems were assayed. Besides that, calorimetry biophysical studies were done analyzing how the thermodynamic parameters are affected by the different lipid compositions e by the presence of the systems anchored enzyme. The enzyme reconstruction to the DPPC constituted liposomes has provided an incorporation of around 80% of the enzyme activity. Thermodynamic studies of the proteoliposomes formed have shown a significant decrease in the H values in relation to the liposomes systems (from 7.63 to 1.88 kcal.mol-1). Binary liposomes constituted of DPPC:Chol in increasing concentrations (9:1, 9:2, 9:3, 7:3, 9:4 e 9:5 molar ratio) were studied by the biophysical parameters as well as by the insertion ability of the enzyme into those systems. A significant decrease in the enthalpy values with the increase of the cholesterol proportion in the liposome was observed. Besides that, the presence of cholesterol has allowed a reduction in the insertion of the catalytic activity in up to 42% when the lipid composition 9:5 DPPPC:Chol was used. Among the binary systems formed with molar ratios of 9:1, the one which showed the highest percentage of TNAP reconstitution was the DPPC:Chol system, with around 62% enzyme incorporation. The tertiary systems had around 30% incorporation of the catalytic activity, and the quaternary system around 25%. Besides the enzymatic activity assays, the enzyme incorporation to the vesicular systems can also be verified by the thermodynamic parameters change detected by DSC. In the calorimetry studies of all the proteoliposomes formed, significant decreases in the enthalpy values were observed when compared to the corresponding liposomes systems. Thereby, the results presented here provide new information that can contribute to understand the alkaline phosphatase behavior in the presence of different microdomain lipid compositions existent in the membrane, as well as understanding the regulation processes of the enzyme during the biomineralization process.