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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 Soluções localizadas em modelos de campos relativísticos e em condensados de Bose-Einstein(Universidade Federal de Goiás, 2010-07-09) CARDOSO, Wesley Bueno; AVELAR, Ardiley Torres; http://lattes.cnpq.br/5732286631137637This work combines some of the results obtained on the study of solitons in relativistic fields and Bose-Einstein condensates. By using a first order formalism to solve the equations of motion of relativistic fields, introduced previously by our group, we construct several classes of lump solutions described by a single real scalar field. We show how these solutions can be controlled depending on a single parameter in the field potential. In condensed matter the solutions of the lump type correspond to bright solitons, very studied in the context of nonlinear crystals, fiber optics, Bose-Einstein condensates, etc. In all these cases, such solutions are obtained via a nonlinear Schr¨odinger equation, responsible for describing the propagation of pulses in optical fibers or crystals, or the atomic density in condensates. In this sense, our main goal is to study the soliton and breather modulations via nonlinear Schrodinger equation. We concentrate on the Bose-Einstein condensate in which the modulation of atomic density can be accomplished through the Feshbach resonance. We study cases where the nonlinearity is described by terms cubic, cubic and quintic, and purely quintic in the nonlinear Schr¨odinger equation. Also, situations where two interacting condensates in which the nonlinear Schr¨odinger equations are coupled, breather modulations, and the study of the soliton behavior under influence of chaotic, random and non-periodic perturbations in the nonlinearity of the system. In many cases we consider the condensate trapped in the cigarshaped configuration, i.e., with freedom in only one spatial dimension. Numerical simulations are performed to verify the stability of the solutions.