Les oligonucléotides antisens possèdent un immense potentiel thérapeutique. Cependant, la faible efficacité avec laquelle ils traversent les membranes biologiques limite leur utilisation. De nombeuses stratégies de délivrances ont été proposées pour contourner ce problème mais la plupart restent peu adaptées à une utilisation in vivo. Durant cette dernière décennie, plusieurs peptides capables de traverser la membrane plasmique ont été caractérisés. Regroupés sour le nom de Cell Penetrating Peptide, ces peptides sont polycationiques et parfois amphipatiques. Nos travaux d'évaluation de ces CPPs dans le modèle cellulaire de correction d'épissage indiquent que ces vecteurs, couplé à des PNA ou PMO, restent bloqués dans les vésicules d'endocytose. L'utilisation d'agents endosomolytiques comme la chloroquine, libère ces conjugués améliorant ainsi l'efficacité de la correction d'épissage. D'une manière générale il est admis que le développement de nouveaux peptides vecteurs présentant une propriété endosomolytique intrinsèque constituerait une avancée majeure dans le domaine de la délivrance. Deux conjugués (R-Ahx-R)4-PMO et R6Pen-PNA corrigent efficacement l'épissage sans addition de chloroquine. Ces conjugués sont internalisés dans les cellules par un mécanisme endocytotique. Les études de structure activité ont indiqué une corrélation entre l'affinité des conjugués aux héparanes sulfates ainsi que de leur hydrophobicité et l'efficacité de correction. Les travaux sur les modèles animaux ont montré une large biodisponibilité du conjugé (R-Ahx-R)4-PMO. Nos collaborations continuent pour améliorer ces deux peptides de délivrance.

Structure and mechanical properties of DNA play a key role in its biological functioning. A lot of well-established conclusions about the DNA structure and its sequence-dependent variabil- ity came from various experimental and computational studies of the Dickerson-Drew dodecamer (DD), a prototypic B-DNA molecule of the sequence (5')CGCGAATTCGCG(3'). In this study we present a detailed analysis of structural and mechan- ical properties of DD based on extensive atomistic molecular dynamics (MD) simulations with explicit representation of wa- ter and ionic environment. We analyze three simulated systems covering different ionic conditions and water models. Two MD trajectories are reported for the first time, one of them being 2.4 µs long. An extensive comparsion with one recent NMR struc- ture and four recent X-ray structures is made. It is found that the end basepairs can adopt two different pairing motifs dur- ing the simulation: the canonical Watson-Crick pair or a non- canonical trans Watson-Crick/Sugar Edge pair. These states can significantly influence the structure of DD even at the third step from the end. A clear relationship is found between the BI/BII backbone substates and the basepair step conformation. A model of rigid bases is used to study mechanical properties of the DNA. The non-local...

Este trabalho consiste em estudar o comportamento eletroquímico de biomoléculas imobilizadas sobre o eletrodo de carbono vítreo, utilizando materiais biocompatíveis como meios imobilizadores para detecções em meios aquosos. Foram utilizados inicialmente compósitos de hidrogéis capazes de auxiliar a permanência da enzima sobre a superfície do eletrodo e beneficiar a transferência de carga entre a enzima e o eletrodo de trabalho. Para melhorar a resposta eletroquímica do biossensor, também foram estudados métodos que utilizam líquidos iônicos no processo de imobilização da enzima. Deste modo a eletroatividade da enzima foi inicialmente estudada por voltametria cíclica, a fim de evidenciar tal eletroatividade no meio totalmente iônico, como também avaliar o melhor método de imobilização, para futuras aplicações em detecções de analitos. Os líquidos iônicos utilizados são compostos por cátions alquil-imidazol com ânions de natureza orgânica ou inorgânica. Como se sabe os íons que compõem o líquido iônico podem distinguir sua funcionalidade, pois é o tamanho desses íons que influencia na maioria das suas propriedades físico-químicas, tais como hidrofobicidade e viscosidade. / The aim of this work is to study the electrochemical behavior of biomolecules immobilized on a glassy carbon electrode, using biocompatible materials as a way for immobilizing detection in aqueous media. Initially, hydrogels composite were used because they are able to assist the permanence of the enzyme on the electrode surface and they are benefit to the charge transfer between enzyme and electrode surface. To improve the electrochemical response of the biosensor, methods using ionic liquids in the process of immobilization of the enzyme were also studied. Thus the electroactivity of the enzyme was initially analyzed by cyclic voltammetry in order to show that the electroactivity remains in an entirely ionic media, as well as evaluating the best method of immobilization, for future applications in biosensors. The ionic liquids used are composed of imidazole-alkyl cations with anions of organic or inorganic nature. As it is well known, the ions in the ionic liquid can distinguish its functionality, due to the fact that it is the size of these ions that influences most on their physicochemical properties such as hydrophobicity and viscosity.

In the present work we performed electronic structure calculations within the Kohn-Sham scheme of the density functional theory (DFT). We studied two molecules with potential applications in life sciences and medicine: ferrioxamine B and 5,10,15,20-tetrakis(1-methyl-4-pyridyl)-21H,23H (TMPyP) porphyrin. We used different methods and different exchange and correlation functionals, analyzing optical and vibrational properties and hyperfine interactions. In the case of ferrioxamine B, results in the crystalline phase (molecular crystal), and gas phase were compared with experimental results obtained using Mössbauer spectroscopy from the literature. We analyzed hyperfine parameters such as the electric quadrupole splitting, asymmetry parameter, hyperfine field and isomer shift. In the case of TMPyP porphyrin we analyzed vibrational properties in the gas phase and optical properties. For the electronic absorption, solvent effects and electronic charges states were analyzed. / In the present work we performed electronic structure calculations within the Kohn-Sham scheme of the density functional theory (DFT). We studied two molecules with potential applications in life sciences and medicine: ferrioxamine B and 5,10,15,20-tetrakis(1-methyl-4-pyridyl)-21H,23H (TMPyP) porphyrin. We used different methods and different exchange and correlation functionals, analyzing optical and vibrational properties and hyperfine interactions. In the case of ferrioxamine B, results in the crystalline phase (molecular crystal), and gas phase were compared with experimental results obtained using Mössbauer spectroscopy from the literature. We analyzed hyperfine parameters such as the electric quadrupole splitting, asymmetry parameter, hyperfine field and isomer shift. In the case of TMPyP porphyrin we analyzed vibrational properties in the gas phase and optical properties. For the electronic absorption, solvent effects and electronic charges states were analyzed.

Protein interactions occurring through biomolecular interfaces play an important role in the circle of life. These interactions are responsible for cellular function, including RNA transcription, protein translation, cell division and cell death among many others. There are different types of interactions based on the strength and the duration of the association. Transient interactions govern most steps of the cellular metabolism, where the associations between two or more molecules are responsive to environmental cues. Among the participants of transient interactions, intrinsically disordered proteins are employed in signaling and other regulatory events within the cell. These proteins exhibit allosteric regulation and gain secondary structure when they bind other proteins or small molecules. In this doctoral thesis work, the biochemical and biophysical principals governing protein associations are investigated and using protein engineering tools, novel biomolecular interfaces are engineered, with potential applications in different areas of biotechnology. The first part of the thesis (Chapter 2) focuses on the investigation of supramolecular enzyme association among tricarboxylic acid cycle enzymes, specifically between citrate synthase and mitochondrial malate dehydrogenase. In this study, the interactions between these enzymes are examined, both among their natural and synthetically produced recombinant versions. In addition, mutational analysis of the amino acid residues at the complex interface was performed to explore the importance of the positively charged patch connecting the active sites of the enzymes. It was discovered that the channeling of the negatively charged intermediate is severely impaired upon mutation of surface residues contributing to the electrostatic channeling. This work provides an important insight into understanding the coupled reaction-transport systems and metabolon formation in general. In addition, it constitutes a great example for substrate channeling in leaky systems, which are relevant to most biological processes. The next section of the thesis (Chapter 3) focuses on an intrinsically disordered peptide, the β-roll. This peptide is isolated from the Block V repeats-in-toxin (RTX) domain of adenylate cyclase from Bordetella pertussis. It is disordered in the absence of calcium and it folds into a β-roll secondary structure composed of two parallel β-sheet faces upon binding to calcium ions. This way, the peptide can transition between its unfolded state and the β-roll structure in a reversible way. We have utilized the allosteric regulation of this domain as a tool to engineer new protein interfaces. In its folded state, the peptide has two faces, serving as binding surfaces available for interaction with other proteins. Our work involved the alteration of the residues, which form these faces upon calcium binding, via combinatorial protein design techniques. The potential of this peptide is evaluated as a cross-linking domain for hydrogel formation. By rationally engineering the two faces of the folded β-roll to contain leucine residues, we have created hydrophobic interfaces, serving as environmentally-responsive cross-linking domains. When there is no calcium, the β-roll domains remain unstructured, delocalizing the leucine rich patches. After calcium binding, the β-rolls fold and the leucine rich faces are exposed creating a hydrophobic driving force for self-assembly. This way, we showed that the β-roll peptide can function as a biomaterials building block capable of proteinaceous hydrogel formation, only in the presence of calcium. The next study (Chapter 4) demonstrates the utilization of this peptide as an alternative scaffold for biomolecular recognition applications. A library of mutant β-rolls was constructed by randomizing the amino acid residues on one of the β-sheet forming faces. Mutant peptides demonstrating an affinity for hen egg white lysozyme were selected, which was chosen as a model target molecule. The thermodynamic parameters of the interactions between the β-roll mutants and the lysozyme were quantified. Upon performing further protein engineering (e.g. concatenation of the single mutants on the DNA level), a mutant with mid-nanomolar affinity was identified. Affinity chromatography experiments showed that this mutant was capable of capturing the target, in the presence of calcium. The captured target was easily released upon removal of the calcium ions. The reversibility of the calcium binding allowed the engineered molecular interface to be controllable. Throughout this study, the β-roll peptide was explored as an allosterically-regulated protein switch for on/off biomolecular recognition, which can be mediated by simply changing the calcium concentration, allowing control over the binding behavior between molecules. The last part of the thesis (Chapter 5) expands on the calcium dependent network formation study. A hydrogel construct was genetically built by fusing the cross-linking β-roll domain and the lysozyme binding β-roll mutant, resulting in a smart biomaterial with dual-functionality. The network-assembly and target capture functions of this construct were tested by various assays including hydrogel erosion experiments. This allosterically-regulated biomaterial exhibited promising results, where calcium-dependent lysozyme entrapment within the assembled network and lysozyme capture on the hydrogel surface were demonstrated. The work presented in this thesis demonstrates different approaches to understand and engineer molecular interfaces in both natural and recombinant systems. In the future, these approaches and the knowledge gained from these studies can be further built upon for different biotechnological applications and can also be applied to other synthetic systems.

Finally, based on theoretical calculations and experiments, we present a development model (DDRA model) to describe the interaction between the protein and its solvent molecule. The parameters derived from this model provide good fits to the experimentally determined complex dielectric constant, making it of the model valuable benchmarks for other theoretical treatments of bio-molecular system. / Secondly, we focus our aims on investigating protein molecules due to the possibility of being able to explain the mechanism of molecular interactions more clearly. Two lands of labeled immunoglobulin G were investigated using a reflective THz-IDS system. The dielectric properties were sensitive to the conjugation of the antibody. Additionally, terahertz spectroscopy is able to evaluate the depth of the hydrogen shell and shows that the hydrogen-bonded networks of charged protein solutions play an important role in determining the dielectric. / The bio-molecular interaction has been one of the most challenging subjects to probe due to its complexity. In the thesis, we have been attempting to answer fundamental questions about bio-molecular interactions in the terahertz (THz) region from the macroscopic to microscopic level. Terahertz radiation (defined as 0.1--10 THz) can excite intermolecular interactions such as the librational and vibrational modes. These attributes make it feasible to probe the dynamic characteristics of the bio-molecular system. Furthermore, it is worth investigating whether terahertz technology could potentially be used as a novel tool in the biomedical diagnosis field in the near future. / Thirdly, using a transmission THz-TDS system we investigated a biomarker protein and observed distinct spectral differences at various temperatures. This work demonstrates that terahertz spectroscopy can be used to evaluate the anharmonicity of the vibrational potential. By comparing the absorption spectra of the THz-TDS and Synchrotron results it is possible to deduce the approximate localization of the vibrational modes within the molecular chain. / We develop a controlled study to investigate the effects of formalin fixing on the THz properties of two different tissue types. The optical properties are measured using THz reflection spectroscopy. The results present how the fixing process can affect image contrast in THz images of biological samples. / Sun, Yiwen. / Advisers: Emma MacPherson; Yuan-ting Zhang. / Source: Dissertation Abstracts International, Volume: 73-03, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 120-140). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Um estudo experimental sobre os aspectos estruturais e dinâmicos de um complexo hidratado de fragmentos de DNA (150 pb) e fases lamelares de lipídios zwitteriônicos é apresentado. Variando-se a hidratação, é possível controlar o confinamento imposto por essa matriz hospedeira sobre os nucleotídeos inseridos na camada aquosa. O arranjo supramolecular do complexo é investigado por difração de raios X e técnicas de microscopia óptica e eletrônica. Um rico polimorfismo de mesofases é observado em função do confinamento. No regime mais hidratado, os fragmentos se distribuem segundo uma orientação nemática entre as membranas. À medida que a quantidade de água diminui, o confinamento das bicamadas sobre os nucleotídeos aumenta e correlações transmembranares aparecem, dando origem a fases altamente organizadas, com simetrias hexagonais 2D de DNA entre as lamelas. A incorporação completa de nucleotídeos é observada apenas quando grandes quantidades de DNA estão presentes. Esse fato aponta para importância maior de interações de volume excluído. Uma análise do parâmetro de Caillé mostra que as flutuações das membranas diminuem com a inserção de DNA. A partir dessas observações,é sugerido que a alteração das interações entre membranas, aliada à aparição de efeitos interfaciais entre DNA e membranas, é um mecanismo relevante no comportamento de fase. As propriedades dinâmicas dos nucleotídeos são investigadas através da técnica de FRAP (fluorescence recovery after photobleaching). Um modelo recentemente desenvolvido para análise de difusão anisotrópica é testado com sucesso, demonstrando estreita correlação entre estrutura e dinâmica. / An experimental study on the structural and dynamical properties of a hydrated DNA zwitterionic lipids complex is presented. By varying the water amount, it is possible to control the connement imposed by this host matrix over the organization of the nucleotides inserted within the water layers. The supramolecular assembly is investigated by X-rays diraction and techniques involving both optical and electron microscopy. A rich polymorphism of mesophases is observed as a function of connement. In the more hydrated regime, the fragments are distributed according to nematic orientation in-between lamellae. As the water amount decreases, the connement of bilayers over the particles increases and transmembrane correlations appear, giving raise to highly-ordered phases, with 2D-hexagonal symmetries of DNA embodied in the lamellar phase. The full incorporation of nucleotides by the lamellar phase is observed only in the presence of large amounts of DNA. This nding points to the major importance of excluded volume interactions. An analysis of the Caillé parameter shows that the insertion of DNA reduces the fluctuations of membranes. From these observations, it is suggested that changes in the interactions between bilayers, together with the appearance of interfacial eects between DNA and membranes, are a relevant mechanism for the phase behavior of these systems. The dynamical properties of nucleotides are investigated through the fluorescence recovery after photobleach (FRAP). A model recently developed for analyses of anisotropic difusion is sucessfully tested, demonstrating a close relationship between structure and dynamics.

Este trabalho consiste em estudar o comportamento eletroquímico de biomoléculas imobilizadas sobre o eletrodo de carbono vítreo, utilizando materiais biocompatíveis como meios imobilizadores para detecções em meios aquosos. Foram utilizados inicialmente compósitos de hidrogéis capazes de auxiliar a permanência da enzima sobre a superfície do eletrodo e beneficiar a transferência de carga entre a enzima e o eletrodo de trabalho. Para melhorar a resposta eletroquímica do biossensor, também foram estudados métodos que utilizam líquidos iônicos no processo de imobilização da enzima. Deste modo a eletroatividade da enzima foi inicialmente estudada por voltametria cíclica, a fim de evidenciar tal eletroatividade no meio totalmente iônico, como também avaliar o melhor método de imobilização, para futuras aplicações em detecções de analitos. Os líquidos iônicos utilizados são compostos por cátions alquil-imidazol com ânions de natureza orgânica ou inorgânica. Como se sabe os íons que compõem o líquido iônico podem distinguir sua funcionalidade, pois é o tamanho desses íons que influencia na maioria das suas propriedades físico-químicas, tais como hidrofobicidade e viscosidade. / The aim of this work is to study the electrochemical behavior of biomolecules immobilized on a glassy carbon electrode, using biocompatible materials as a way for immobilizing detection in aqueous media. Initially, hydrogels composite were used because they are able to assist the permanence of the enzyme on the electrode surface and they are benefit to the charge transfer between enzyme and electrode surface. To improve the electrochemical response of the biosensor, methods using ionic liquids in the process of immobilization of the enzyme were also studied. Thus the electroactivity of the enzyme was initially analyzed by cyclic voltammetry in order to show that the electroactivity remains in an entirely ionic media, as well as evaluating the best method of immobilization, for future applications in biosensors. The ionic liquids used are composed of imidazole-alkyl cations with anions of organic or inorganic nature. As it is well known, the ions in the ionic liquid can distinguish its functionality, due to the fact that it is the size of these ions that influences most on their physicochemical properties such as hydrophobicity and viscosity.

Este trabalho de mestrado trata da implementação de um espectrômetro de correlações angulares perturbadas no Laboratório do Acelerador Pelletron do Instituto de Física da Universidade de São Paulo. O espectrômetro é formado por seis detectores cintiladores com cristais de \'BaF IND.2\', de 3 polegadas de diâmetro por 6 de comprimento, com um sistema eletrônico e de aquisição de dados multiparamétrico padrão CAMAC. Diferentemente do usual, os espectros de energia dos raios gama dos núcleos de prova são adquiridos para cada detector, o que permite manter um controle maior sobre todo o experimento. Além disso, um mesmo experimento pode ser revisto com diferentes abordagens por diversas vezes, pois todas as informações sobre ele são armazenadas. Com a configuração eletrônica adotada, os espectros de energia são obtidos por meio de um QDC (charge to digital converter), dispensando o uso de pré-amplificadores. Os espectros de tempo são adquiridos com um TDC (time do digital converter). A seleção dos eventos de coincidência é realizada computacionalmente, procedimento que pode ser realizado durante a aquisição dos dados. Como a motivação para a implementação desse espectrômetro é o estudo de estruturas e interações de biomoléculas por meio da técnica de correlações angulares (PAC), foram realizadas medidas exploratórias, com o uso do espectrômetro do Laboratório de interações Hiperfinas (LIH) do Centro do Reator de Pesquisas (CRPq) no IPEN, paralelamente à implementação do espectrômetro. As primeiras medições foram realizadas com amostras de vesículas lipídicas. Com essas medidas foi possível notar a influência da variação de tamanho das moléculas (diminuição de tamanho em uma ordem de grandeza) no tempo de correlação rotacional à temperatura ambiente, quando adicionado SDS (sodium dodecyl sulfate) na suspensão para formação de um agregado micelar. As duas séries de medidas seguintes foram realizadas com amostras de SDS nas quais variaram-se as concentrações para se tentar verificar alterações na geometria ou na mobilidade das moléculas em função desse parâmetro. Foi possível notar que o comportamento das funções perturbação experimentais variaram com as amostras, porém não foi possível notar sistemática no comportamtento. Outro fator notado foi a influência do meio. O comportamento das moléculas quando na presença de metanol nas amostras era bem diferente das soluções aquosas. Também não foi possível obter uma conclusão clara quanto à concentração micelar crítica para soluções aquosas. Por fim foram realizadas medidas com amostras de proteína calmodulina. Foram feitas medidas à temperatura ambiente e a 77K. Notou-se que essa proteína é passível de ser estudada por meio da técnica PAC. Para confirmar a presença da proteína nas amostras e também tentar verificar um deslocamento na massa devido à presença do íon \'ANTPOT.111 Cd\' \'ANTPOT.2+\' foram realizadas medidas de espectrometria de massas no Laboratório de Espectrometria de Massas na Embrapa em Brasília. Foi possível confirmar a presença da proteína nas amostras, porém não foi possível notar a presença de \'ANTPOT.111 Cd\' devido à baixa concentração de íons utilizados com a técnica PAC. / This work is related to the implementation of a perturbed angular correlation (PAC) spectrometer at the University of São Paulo Pelletron Laboratory. The spectrometer consists of 6 cylindrical BaF$_2$ scintillator detectors, with 3 inches diameter and 6 inches length and a multiparameter CAMAC data acquisition system. Different from usual, the gamma ray energy spectra of the cascade nuclei are acquired for each detector, which allows us to have more control of the experiment. Besides, the same experiment can be revised with different approaches at any time. With the adopted electronics configuration, the energy spectra are obtained through a QDC (charge to digital converter) module, which dispenses the use of pre-amplifiers. The time spectra are acquired with a TDC (time to digital converter) module. The selection of coincidence events is performed computationally, and this procedure can be evaluated during the data acquisition. The main motivation for implementing this spectrometer is the study of the structure and interactions of biomolecules through the perturbed angular correlation technique. Test measurements were performed, parallel to the spectrometer construction, with the use of the Hyperfine Interactions Laboratory spectrometer at the Centro do Reator de Pesquisas do Instituto de Pesquisas Energéticas e Nucleares (CRPq-IPEN). The first measurements were performed with lipidic vesicles samples. In this case it was possible to observe the influence of the molecule dimension change (decrease in one order) on the rotational correlation time at room temperature, when SDS (sodium dodecyl sulfate) was added in the suspension to form micellar aggregation. The two following series of measurements were performed with SDS samples in which the concentration was varied in order to verify modifications in the geometry or mobility of the molecules as a function of that parameter. The behavior of the experimental perturbation functions varied with the samples. However, it was not possible to point out any systematics in their behavior. The molecules behavior when in presence of methanol in the samples was very different from the aqueous solutions. Also, it was not possible to obtain a clear conclusion about the critical micellar concentration for the aqueous solutions. Finally, the last measurements were performed with calmodulin protein samples, at room temperature and at 77K. In this case we concluded that this protein can be studied through the PAC technique. In order to confirm the presence of the protein in the samples and at same time to verify if any mass displacement occurred due to the presence of the $^{111}$Cd$^{2+}$, mass spectrometry measurements were performed at the Laboratório de Espectrometria de Massas -- Embrapa in Brasília. It was possible to confirm the presence of the protein in the samples, but it was not possible to observe the mass displacement due to the presence of the $^{111}$Cd, since the ions concentration used with the PAC technique is very low.

Este trabalho de mestrado trata da implementação de um espectrômetro de correlações angulares perturbadas no Laboratório do Acelerador Pelletron do Instituto de Física da Universidade de São Paulo. O espectrômetro é formado por seis detectores cintiladores com cristais de \'BaF IND.2\', de 3 polegadas de diâmetro por 6 de comprimento, com um sistema eletrônico e de aquisição de dados multiparamétrico padrão CAMAC. Diferentemente do usual, os espectros de energia dos raios gama dos núcleos de prova são adquiridos para cada detector, o que permite manter um controle maior sobre todo o experimento. Além disso, um mesmo experimento pode ser revisto com diferentes abordagens por diversas vezes, pois todas as informações sobre ele são armazenadas. Com a configuração eletrônica adotada, os espectros de energia são obtidos por meio de um QDC (charge to digital converter), dispensando o uso de pré-amplificadores. Os espectros de tempo são adquiridos com um TDC (time do digital converter). A seleção dos eventos de coincidência é realizada computacionalmente, procedimento que pode ser realizado durante a aquisição dos dados. Como a motivação para a implementação desse espectrômetro é o estudo de estruturas e interações de biomoléculas por meio da técnica de correlações angulares (PAC), foram realizadas medidas exploratórias, com o uso do espectrômetro do Laboratório de interações Hiperfinas (LIH) do Centro do Reator de Pesquisas (CRPq) no IPEN, paralelamente à implementação do espectrômetro. As primeiras medições foram realizadas com amostras de vesículas lipídicas. Com essas medidas foi possível notar a influência da variação de tamanho das moléculas (diminuição de tamanho em uma ordem de grandeza) no tempo de correlação rotacional à temperatura ambiente, quando adicionado SDS (sodium dodecyl sulfate) na suspensão para formação de um agregado micelar. As duas séries de medidas seguintes foram realizadas com amostras de SDS nas quais variaram-se as concentrações para se tentar verificar alterações na geometria ou na mobilidade das moléculas em função desse parâmetro. Foi possível notar que o comportamento das funções perturbação experimentais variaram com as amostras, porém não foi possível notar sistemática no comportamtento. Outro fator notado foi a influência do meio. O comportamento das moléculas quando na presença de metanol nas amostras era bem diferente das soluções aquosas. Também não foi possível obter uma conclusão clara quanto à concentração micelar crítica para soluções aquosas. Por fim foram realizadas medidas com amostras de proteína calmodulina. Foram feitas medidas à temperatura ambiente e a 77K. Notou-se que essa proteína é passível de ser estudada por meio da técnica PAC. Para confirmar a presença da proteína nas amostras e também tentar verificar um deslocamento na massa devido à presença do íon \'ANTPOT.111 Cd\' \'ANTPOT.2+\' foram realizadas medidas de espectrometria de massas no Laboratório de Espectrometria de Massas na Embrapa em Brasília. Foi possível confirmar a presença da proteína nas amostras, porém não foi possível notar a presença de \'ANTPOT.111 Cd\' devido à baixa concentração de íons utilizados com a técnica PAC. / This work is related to the implementation of a perturbed angular correlation (PAC) spectrometer at the University of São Paulo Pelletron Laboratory. The spectrometer consists of 6 cylindrical BaF$_2$ scintillator detectors, with 3 inches diameter and 6 inches length and a multiparameter CAMAC data acquisition system. Different from usual, the gamma ray energy spectra of the cascade nuclei are acquired for each detector, which allows us to have more control of the experiment. Besides, the same experiment can be revised with different approaches at any time. With the adopted electronics configuration, the energy spectra are obtained through a QDC (charge to digital converter) module, which dispenses the use of pre-amplifiers. The time spectra are acquired with a TDC (time to digital converter) module. The selection of coincidence events is performed computationally, and this procedure can be evaluated during the data acquisition. The main motivation for implementing this spectrometer is the study of the structure and interactions of biomolecules through the perturbed angular correlation technique. Test measurements were performed, parallel to the spectrometer construction, with the use of the Hyperfine Interactions Laboratory spectrometer at the Centro do Reator de Pesquisas do Instituto de Pesquisas Energéticas e Nucleares (CRPq-IPEN). The first measurements were performed with lipidic vesicles samples. In this case it was possible to observe the influence of the molecule dimension change (decrease in one order) on the rotational correlation time at room temperature, when SDS (sodium dodecyl sulfate) was added in the suspension to form micellar aggregation. The two following series of measurements were performed with SDS samples in which the concentration was varied in order to verify modifications in the geometry or mobility of the molecules as a function of that parameter. The behavior of the experimental perturbation functions varied with the samples. However, it was not possible to point out any systematics in their behavior. The molecules behavior when in presence of methanol in the samples was very different from the aqueous solutions. Also, it was not possible to obtain a clear conclusion about the critical micellar concentration for the aqueous solutions. Finally, the last measurements were performed with calmodulin protein samples, at room temperature and at 77K. In this case we concluded that this protein can be studied through the PAC technique. In order to confirm the presence of the protein in the samples and at same time to verify if any mass displacement occurred due to the presence of the $^{111}$Cd$^{2+}$, mass spectrometry measurements were performed at the Laboratório de Espectrometria de Massas -- Embrapa in Brasília. It was possible to confirm the presence of the protein in the samples, but it was not possible to observe the mass displacement due to the presence of the $^{111}$Cd, since the ions concentration used with the PAC technique is very low.