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Item Interações da albumina de soro bovino com surfactantes e efeitos de antioxidantes sobre a oxidação de lipoproteínas de baixa densidade induzida por íons de cobre(Universidade Federal de Goiás, 2012-08-02) ANJOS, Jorge Luiz Vieira dos; ALONSO, Antônio; http://lattes.cnpq.br/5013069863616789Human plasma contains primarily large proteins, ranging in composition and concentration as the individual's physiological state. Among these proteins, albumin and low density lipoprotein (LDL) have been widely studied. The albumin (the most abundant protein in blood plasma) is responsible for important functions in the human body due to its excellent ability to bind and transport small molecules. In turn, the LDL (responsible for transporting cholesterol to the cells) in its oxidized form is directly associated with atherosclerosis, the main cause of cardiovascular disease. In the first part of this work, the interaction of bovine serum albumin (BSA) with the ionic surfactants sodium dodecylsulfate (SDS), cetyltrimethylammonium chloride (CTAC) and N-hexadecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (HPS) was studied by electron paramagnetic resonance (EPR) spectroscopy of spin label covalently bound to the single free thiol group of the protein. In the second part was studied the oxidation of human LDL by copper ions and also the antioxidant potential of polyphenols resveratrol, (+)-catechin and quercetin, using the EPR of a spin label, derived from stearic acid (5-DSA), and the method malondialdehyde content (MDA). Part I: The dynamics of the BSA and the thermodynamic parameters for transferring the nitroxide side chain from the more motionally restricted to the less restricted component were monitored through EPR spectra simulation. Whereas SDS and CTAC showed similar increases in the dynamics of the protein backbone for all concentrations used, HPS presented a smaller effect at concentrations above 1.5mM. At 10mM of surfactants and 0.15 mM BSA, the standard Gibbs free energy change was consistent with protein backbone conformations more expanded and exposed to the solvent, but with a less pronounced effect for HPS. In the presence of the surfactants, the enthalpy change, related to the energy required to dissociate the nitroxide side chain from the protein, was greater, suggesting a lower water activity. The nitroxide side chain also detected a higher viscosity environment in the vicinity of the Mal-5 induced by the addition of the surfactants. The results suggest that the surfactant-BSA interaction, at higher surfactant concentration, is affected by the affinities of the surfactant to its own micelles and micelle-like aggregates. Complementary DLS (Dynamic Light Scattering) data suggests that the temperature induced changes monitored by the Mal-5 reflects local changes in the vicinity of Cys-34 BSA residue. Part II: The oxidative process induced by copper ions results in lipid peroxidation of LDL (evidenced by high concentration of MDA) could also be monitored by the decrease in the dynamics of 5-DSA, reflected in increased spectral parameter 2A//. The oxidation of LDL resulted in increased energy barrier that the spin labels must overcome to achieve higher degrees of motion. All polyphenols studied were able to protect LDL completely against oxidation for concentrations from 30 M, whereas the protection provided by the Butylated hydroxytoluene (BHT) occurred only partially. This result, based on data from the literature, was attributed to the ability of polyphenols act as scavenger and chelating agents, while the BHT acts just like scavenger due the presence of only a single hydroxyl group in its molecule.Item Dinâmica molecular e particionamento do marcador de spin di-terc-butil nitróxido em membranas de estrato córneo. Efeito de Terpenos(Universidade Federal de Goiás, 2009-03-31) CAMARGOS, Heverton Silva de; ALONSO, Antônio; http://lattes.cnpq.br/5013069863616789Terpenes are a very promising class of skin penetration enhancers especially due to their low potential of irritation in the skin. In this work, we have used the electron paramagnetic resonance (EPR) spectroscopy of the small spin label di-tert-butyl nitroxide (DTBN), which partitions the aqueous and hydrocarbon phases, to study the interaction of the terpenes ®-terpineol, 1,8-cineole, L(-)-carvone and (+)-limonene with the uppermost skin layer, the stratum corneum, and the membrane models of 1,2-dipalmitoyl-sn-glycero- 3-phosphatidylcholine (DPPC) and 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC). The EPR spectra indicated that the terpenes increase both the partition coe±cient and the rotational di®usion rate of the spin labels in the stratum corneum membranes whereas for DMPC and DPPC bilayers were observed similar e®ects only at temperatures below the liquid-crystalline phase. The EPR parameter associated to probe polarity inside the membranes showed thermotropic induced changes, suggesting relocations of spin probe, which were dependent of the membrane phases. While DMPC and DPPC bilayers showed abrupt changes in the partitioning and rotational correlation time parameters at the phase transitions, the SC membranes were characterized by slights changes in whole interval of measured temperatures, presenting the greatest changes or membranes reorganizations in the temperature range of v50 to v74±C. The results suggest that the terpenes act as spacers that weaken the hydrogen-bonded network at the polar interface thus °uidizing the stratum corneum lipids and, in consequence, increase the permeation of small polar molecules across the membranes. 2Item Estudo da atividade antioxidante do 4-nerolidilcatecol por métodos analíticos e biofísicos(Universidade Federal de Goiás, 2011-08-17) FERNANDES, Kelly de Souza; ALONSO, Antônio; http://lattes.cnpq.br/5013069863616789NOTE: As programs do not copy or copy errors with certain symbols, formulas, formatting ... etc, to view the summary and the entire file, click rm PDF - dissertation at the bottom of the screen.