A cinética enzimática dos derivados de quinizarina com cadeias homólogas por lipases imobilizadas foi investigada por espectroscopia de fluorescência. Este estudo foi realizado em nível macroscópico e microscópico. Para o estudo macroscópico, foi utilizada a lipase suportada CALB (Novozyme® 435) e para o estudo microscópico a lipase Rhizopus niveus imobilizada em nanopartículas de sílica. Os derivados de quinizarina são espécies que não apresentam fluorescência, porém, quando são hidrolisados, tornam-se fluorescentes (quinizarina). Com um modelo cinético considerando um mecanismo de dois processos sequenciais do tipo Michaelis-Menten, foi possível fazer uma descrição adequada da evolução temporal da formação da quinizarina. O tempo médio de reação da hidrólise enzimática, em nível macroscópico, foi determinado para os derivados diacetato, dibutirato, dihexanoato e dioctanoato de quinizarina nos solventes hexano, ciclo-hexano e decalina saturados com água. No estudo microscópico, a lipase de Rhizopus niveus foi incorporada em nanopartículas de sílica de 200nm. A hidrólise enzimática foi monitorada por imagens e pela flutuação da intensidade de fluorescência com o tempo, por meio da microscopia de fluorescência confocal. Os resultados mostraram que, após a adição do substrato (derivados da quinizarina), começam a aparecer regiões fluorescentes devido ao trabalho enzimático (formação da quinizarina). As imagens de microscopia de fluorescência confocal não mostraram uma nítida diferença entre os substratos avaliados. Entretanto, o estudo da flutuação da intensidade de fluorescência mostrou que há uma diferença entre os substratos e que é possível estimar constantes de tempo de relaxação da atividade enzimática. Além disso, a atividade da lipase depende da forma em que a mesma está distribuída nas nanopartículas (ligada ou adsorvida) e também do tamanho da cadeia de alquílica que compões os derivados. O decaimento de fluorescência da quinizarina produzida pela hidrólise dos derivados pela lipase foi adquirido por microscopia de fluorescência confocal usando excitação de 2-fótons. / The kinetics of enzymatic hydrolysis of quinizarin diester by supported lipase dispersed beads in organic solvents was investigated by fluorescence spectroscopy. This study was performed on macroscopic and microscopic levels. For the macroscopic study was used CALB immobilized lipase (Novozyme ® 435) on acrylate beads, and for microscopic study Rhizopus niveus lipase immobilized on silica nanoparticles. The quinizarin derivatives (substrates) are non-fluorescent species, and only the end product quinizarin has fluorescence. A kinetic model considering two sequential Michaelis-Menten mechanisms provides a suitable description of the time evolution of the quinizarin formation monitored by emission spectroscopy and photon counting measurements. The average reaction time of the enzymatic hydrolysis was determined for quinizarin diacetate, dibutirate, dihexanoate and dioctanoate in hexane, cyclohexane and decaline water saturated solvents. In the microscopic study, the Rhizopus niveus lipase was dispersed into and bound silica mesoporous 200nm particles. In both systems, dispersed silica nanoparticles and a small fraction of aggregates are found in thin film. The enzyme activity was monitored by images and fluctuations of fluorescence intensity over time using confocal fluorescence microscopy. The results showed that after addition of substrate fluorescent spots due to enzyme activity start to appear. Confocal fluorescence images showed no clear difference among substrates. However, the study of fluorescence intensity fluctuations showed that enzyme activity depends on the type of substrate and enzyme support. In addition, the lipase activity depends on the form in which it is distributed in the nanoparticles (bound or entrapped) and the size of the alkyl diester derivatives. The fluorescence decay of quinizarin produced by lipase hydrolysis of diester was measured by confocal fluorescence microscopy using 2-photon pulse excitation.

Sistemas nanocarreadores de moléculas orgânicas têm emergido como promissores sistemas para aplicação na terapêutica e/ou diagnóstico. No presente trabalho foram desenvolvidas nanocápsulas poliméricas contendo, em seus diferentes domínios, sondas fluorescentes capazes de fornecer imagem quando analisadas em microscópio de fluorescência confocal, mostrando as potencialidades do sistema como agente para imagem ótica. Uma importante característica de moléculas propostas como marcadores fluorescentes, é que não haja sobreposição dos espectros de absorção e emissão de fluorescência. Para tanto, foi utilizado um corante sintético do grupo dos benzoxazólicos (HBO-C8) para marcação do núcleo lipofílico, e os polímeros PCL e quitosana foram ligados covalentemente aos corantes rodamina B e alaranjado de acridina, respectivamente. As formulações desenvolvidas e caracterizadas com dois ou três marcadores apresentaram caráter nanotecnológico e as fotomicrografias de transmissão revelaram que as nanopartículas contendo HBO-C8 e PCL-Rho (sem quitosana), preservou a morfologia da nanopartícula. Adicionalmente, o HBO-C8 foi quantificado na formulação contendo HBO-C8 e PCL-Rho, onde verificou-se que 98% do corante está internalizado na nanopartícula, alcançando assim, o objetivo proposto de usá-lo como sonda para marcação do núcleo lipofílico. Por meio da microscopia de fluorescência confocal, foram obtidas imagens dos marcadores fluorescentes colocalizados, para as formulações contendo dois ou três domínios fluorescentes, demonstrando que essas nanocápsulas podem ser propostas como uma plataforma promissora para serem empregadas como sondas para imagem ótica. / Nanocarriers systems of organic molecules have emerged as promising systems for application in therapy and diagnosis. In the present study polymeric nanocapsules containing fluorescent probes in their different domains, capable of providing image when analyzed in confocal fluorescence microscope, showing the potential of the system as an agent for optical imaging. An important feature of proposed molecules as fluorescent probes, there is no overlap of the spectra of absorption and fluorescence emission. Thus, a group of synthetic dye benzoxazólicos (HBO-C8) to mark the lipophilic core, and PCL and chitosan polymers were covalently linked to dye rhodamine B and acridine orange , respectively. The formulations developed and characterized with two or three markers showed nanotechnological character and transmission photomicrographs showed that nanoparticles containing PCL-Rho and HBO-C8 (without chitosan) preserved morphology of the nanoparticle. Additionally, the HBO-C8 was was quantified on formulation contained HBO-C8 and PCL-Rho, where it was found that 98% of the dye is internalized in the nanoparticle thus reaching the purpose proposed to use as a probe for marking the lipophilic core . By images of confocal fluorescence microscopy were obtained the colocalized of fluorescent markers to formulations containing two or three fluorescent domains, demonstrating that these nanocapsules can be proposed as a promising platform to be used as probes for optical image.

Há no organismo humano Glutationas peroxidases (GPx), muitas dessas responsáveis por proteger as células contra espécies reativas de oxigênio (ROS, do inglês Reactive Oxygen Species), cuja detecção pode ser realizada por sondas fluorescentes. Tais sondas podem conter em sua estrutura átomos de selênio ou telúrio. Esses calcogênios apresentam várias propriedades, dentre elas a suscetibilidade a processos oxidativos, que podem levar a mecanismos de transferência eletrônica fotoinduzida (PET), promovendo um sistema on/off de fluorescência na molécula. Sendo assim os derivados de selenoaminoácidos e sondas fluorescentes contendo calcogênios podem ser empregados tanto na eliminação de espécies reativas de oxigênio como na sua detecção. O presente trabalho propôs a síntese de derivados de selenoaminoácidos, via reações do tipo Morita-Baylis-Hillman, que poderiam ser empregados como antioxidante. Entretanto, foi também foco da nossa pesquisa explorar a síntese de novos composto organocalcogênios com propriedades fluorescentes e seu estudo fotofísico / Glutathione peroxidases (GPx) are enzymes present in the human body, and many of them are responsible for protecting cells against reactive oxygen species (ROS), which can be detected by fluorescent probes. Selenium or tellurium atoms can be present in these probes and are susceptible to oxidative processes, which can lead to photoinduced electron transfer mechanism (PET). These mechanisms can promote an on/off fluorescence system, thus, selenium amino acids derivatives and fluorescent probes containing chalcogens can be used both in the elimination of reactive oxygen species and their detection. Herein, we proposed the synthesis of selenium amino acids derivatives, vía Morita-Baylis-Hillman reaction, and the products were pointed out as potential antioxidants. In addition, it was also the focus of our research exploring the synthesis of new organochalcogen compounds with fluorescent properties and their photophysical study.

As condições do trato reprodutivo da fêmea, assim como a qualidade do sêmen são fatores que interferem na fertilidade. Os objetivos deste trabalho foram avaliar a resposta inflamatória uterina e a taxa de prenhez em éguas, considerando hemodinâmica uterina e citologia endometrial após a inseminação artificial (IA) com sêmen congelado de alta e baixa qualidade. Para o presente estudo foram realizados dois experimentos. No Experimento 1 foram utilizadas 15 éguas distribuídas de forma aleatória em quatro grupos: CT - controle: mimetização do procedimento de IA (n=7), DIL: infusão intrauterina de diluidor a base de leite desnatado (n=7), ALTA: IA com sêmen de alta qualidade (n=7), e BAIXA: IA com sêmen de baixa qualidade (n=7). A avaliação uterina foi realizada por ultrassonografia transretal com Doppler nos modos Espectral e Color-flow em sete momentos: prévio à indução da ovulação (TIO), imediatamente antes da IA (TIA), 2 (T2), 6 (T6), 12 (T12), 24 (T24) e 48 horas (T48) após a IA. Foram considerados os valores de índice de resistência (RI) da artéria uterina e de escore de vascularização (EV) uterino. A citologia uterina foi realizada 6 h após a IA. No Experimento 2 foram utilizadas 12 éguas, e seus ciclos foram distribuídos nos tratamentos: CT - controle: mimetização do procedimento de IA (n=8), DIL: infusão intrauterina de diluidor (n=8), ALTA: IA com sêmen de alta qualidade (n=8), e BAIXA: IA com sêmen de baixa qualidade (n=8). O delineamento experimental foi em Quadrado Latino 4X4. A avaliação uterina foi realizada por ultrassonografia transretal com Doppler modos Espectral e Color-flow em três momentos: prévio à indução da ovulação (TIO), imediatamente antes da IA (TIA) e 6 horas (T6) após a IA. A citologia uterina foi realizada 6 h após a IA. Neste experimento foi considerada a taxa de prenhez comparando-se os ciclos utilizados para os grupos ALTA e BAIXA. O diagnóstico de gestação foi realizado 14 dias após a ovulação. Foi utilizado o procedimento misto (PROC MIXED) do SAS (Versão 9.3) para a análise estatística e foi considerada diferença significativa quando p ≤0,05. No Experimento 1, não foi encontrada diferença estatística entre os grupos para os valores de hemodinâmica uterina RI e EV. Houve aumento significativo de células inflamatórias no endométrio de éguas inseminadas com sêmen de baixa qualidade, porém não diferiu do grupo de éguas inseminadas com sêmen de alta qualidade. No Experimento 2, não houve diferença estatística entre os grupos para os valores de RI, mas se observou maior EV uterino nos grupos inseminados com sêmen de alta e de baixa qualidade quando comparados com o grupo controle. Na citologia uterina não foi encontrada diferença estatística. A taxa de prenhez para os grupos ALTA (81,82%) e BAIXA (54,55%) não foi estatisticamente diferente. Conclui-se que a deposição de sêmen no útero, leva a um processo inflamatório do endométrio, e esta pode alterar a hemodinâmica uterina detectável por ultrassonografia Doppler em éguas. Não existe diferença significativa na resposta inflamatória entre as qualidades de sêmen. A inseminação com sêmen congelado de menor qualidade não altera a taxa de prenhez, mas são necessários mais estudos para verificar esta diferença. / The female reproductive tract soundness, as well as semen quality are factors that interfere in fertility. The aims of this study were to evaluate inflammatory uterine response and pregnancy rate in mares, considering uterine hemodynamics and endometrial cytology after artificial insemination (IA) with frozen semen of high and low quality. Two experiments were executed for the present study. For Experiment 1, fifteen mares were randomly distributed between four groups: CT - control: mimic of the procedure of IA (n=7), DIL: intrauterine infusion of skim milk semen extender (n=7), ALTA: IA with high quality semen (n=7), and BAIXA: IA with low quality semen (n=7). Uterine evaluation was done using transrectal Doppler ultrasonography by Spectral and Color-flow modes on seven moments: immediately before ovulation induction (TIO), immediately before AI (TIA), 2 (T2), 6 (T6), 12 (T12), 24 (T24) and 48 (T48) hours after IA. There were considered the numerical values of resistance index (RI) of uterine arteries and vascularity scores (EV) of uterine horns. Endometrial cytology was done at 6 h after IA. On Experiment 2, were used 12 mares which their cycles were distributed between the treatments: CT - control: only mimic of IA procedure (n=8), DIL: intrauterine infusion of semen extender (n=8), ALTA: IA with high quality semen (n=8), and BAIXA: IA with low quality semen (n=8). The experimental design was a Latin Square. Uterine evaluation was done using transrectal Doppler ultrasonography by Spectral and Color-flow modes on three moments: before ovulation induction (TIO), immediately before AI (TIA) and 6 hours (T6) after IA. Endometrial cytology was done at 6 h after IA. In this experiment it was considered the pregnancy rate comparing the cycles for groups ALTA e BAIXA. The pregnancy diagnosis was done 14 days after ovulation. It was used the Mixed Procedure (PROC MIXED) from SAS (Version 9.3) for statistical analysis and significant difference was considered when p≤0.05. On Experiment 1, no statistical difference was found between the groups for uterine hemodynamic values RI and EV. There was a significant increase of inflammatory cells on the mares inseminated with low quality semen, however it wasnt different from the group if mares inseminated with high quality semen. On Experiment 2, there was no statistical difference between the groups for RI values, but the uterine EV was higher for the groups inseminated with high and low quality when compared with the control group. There was no statistical difference on endometrial cytology. There was no statistical difference on pregnancy rate for the groups ALTA (81,82%) and BAIXA (54,55%). As a conclusion, the deposition of semen in the uterus causes an inflammatory process on the endometrium, and it could alter uterine dynamics detected by Doppler ultrasonography in mares. It does not exist significant difference on the inflammatory response between semen qualities. Low quality frozen-semen insemination does not alter pregnancy rate, but more studies are necessary in order to verify this difference.

A hemoglobina de Glossoscolex paulistus (HbGp) é caracterizada por uma massa molecular de 3.600 kDa, alta estabilidade oligomérica, resistência a auto-oxidação, e alta afinidade em ligar oxigênio. A estrutura quaternária desta proteína apresenta 144 cadeias com grupo heme (globinas) e 36 cadeias sem grupo heme (linkers), dispostos em duas camadas hexagonais. No presente trabalho, foi realizado o estudo da estabilidade da oxi-HbGp frente aos processos de dissociação oligomérica e desnaturação, utilizando duas classes de desnaturantes, ou seja, o surfactante brometo de dodeciltrimetilamônio (DTAB), e os agentes caotrópicos cloridrato de guanidina (GuHCl) e ureia. Convém mencionar ainda, que este estudo foi desenvolvido através do uso de duas sondas fluorescentes, 1-Anilino-8-naftaleno-sulfonato (1,8-ANS) e fluoresceína isotiocianato (FITC), usando as técnicas de absorção óptica, fluorescência estática, espalhamento de luz dinâmico (DLS) e fluorescência resolvida no tempo. Os resultados de fluorescência estática mostram que o DTAB induz um aumento na intensidade de emissão de fluorescência da sonda ANS, com o deslocamento do máximo de emissão para o azul de 517 para 493 nm. Duas transições são observadas, em 2,5 e 9,5 mmol/L de DTAB, e estão associadas à interação da sonda ANS com agregados pré-micelares e micelas, respectivamente. Na oxi-HbGp, ANS liga a sítios menos expostos ao solvente, quando comparado às micelas de DTAB, caracterizados pela emissão em 467-472 nm. A adição de DTAB ao sistema oxi-HbGp-ANS, no pH 7,0, induz a agregação da proteína, a dissociação oligomérica e desenovelamento da oxi-HbGp. No pH 5,0, a formação de agregados não foi observada. Além disso, o processo de desenovelamento induzido pelo DTAB apresenta duas transições, a primeira em virtude da dissociação oligomérica, e a segunda, provavelmente, devido à desnaturação das subunidades dissociadas. Por outro lado, GuHCl e ureia com concentrações acima de 1,5 e 4,0 mol/L respectivamente, induzem a desnaturação completa da oxi-HbGp, com redução dos grupos hidrofóbicos na superfície da proteína, e o deslocamento do ANS para o meio aquoso, detectado pela redução de intensidade de fluorescência. A técnica de fluorescência resolvida no tempo permitiu avaliar os valores dos tempos de vida para a sonda 1,8-ANS, bem como, para oxi-HbGp. Por último, a oxi-HbGp foi marcada com a sonda covalente fluoresceína isotiocianato (FITC) em dois valores de pH 7,0 e 9,0, e nas proporções sonda:heme de 1:5 e 2:1. A quantidade de FITC efetivamente ligada a oxi-HbGp por heme foi estimada a partir dos dados de absorção óptica. Supondo que o rendimento quântico de FITC no tampão é 100%, os rendimentos quânticos de FITC ligada a oxi-HbGp também foram encontrados. Além disso, estudos preliminares de dissociação e desnaturação da oxi-HbGp marcada com FITC, na presença do surfactante DTAB, foram realizados. / Glossoscolex paulistus hemoglobin (HbGp) is characterized by a molecular mass of 3,600 kDa, a high oligomeric stability, resistance to oxidation and a high affinity to oxygen. The quaternary structure of this macromolecule consists of 144 globin chains, and 36 additional chains lacking the heme group, named linkers, organized in a double-layered hexagonal structure. In this study, the oxy-HbGp stability, as well as, the oligomeric dissociation and unfolding processes were studied, using two types of denaturants,the surfactant Dodecyl-trimethylammonium bromide (DTAB), and chaotropic agents guanidine hydrochloride (GuHCl) and urea. Moreover, this study was developed based on 8-anilino-1-naphtalene-sulfonic acid (ANS) and fluorescein isothiocyanate (FITC) fluorescence probes, using the techniques of optical absorption, static fluorescence, dynamic light scattering (DLS) and time resolved fluorescence. The results of static fluorescence show that dodecyl-trimethylammonium bromide (DTAB) induces an increase in ANS fluorescence emission intensity, with maximum emission wavelength blue-shifted from 517 to 493 nm. Two transitions are noticed, at 2.50 and 9.50 mmol/L of DTAB, assigned to ANS interaction with pre-micellar aggregates and micelles, respectively. In oxy-HbGp, ANS binds to protein sites less exposed to solvent, as compared to DTAB micelles, characterized by emission at 467 - 472 nm. At pH 7.0, the addition of DTAB to the oxy-HbGp-ANS system induced the protein aggregation, oligomeric dissociation and unfolding of oxy-HbGp. At pH 5.0, no formation of aggregates was observed. Moreover, DTAB-induced unfolding process displays two transitions, one due to oligomeric dissociation and the second one, probably, due to the denaturation of dissociated subunits. On the other hand, guanidine hydrochloride (GuHCl) and urea, at concentrations above 1.5 and 4.0 mol/L, respectively, induce the full HbGp denaturation, with reduction of ANS-bound oxy-HbGp hydrophobic patches on the surface of the proteins. The shift of ANS to the aqueous medium was detected by the reduction in the fluorescence intensity. Time resolved fluorescence technique allowed to evaluate the lifetimes of ANS, as well as, for oxy-HbGp. Finally, oxy-HbGp was labeled with covalent probe fluorescein isothiocyanate (FITC), at pH values 7.0 and 9.0, and at probe: heme ratios of 1:5 and 2:1. The quantity of FITC effectively bound to oxy-HbGp, on the heme basis was estimated from the optical absorption data. Assuming a 100% quantum yield for FITC in buffer, the quantum yield of FITC bound to oxy-HpGp was also estimated. In addition, preliminary studies of dissociation and denaturation of oxy-HbGp labeled with FITC, in the presence of DTAB surfactant, were accomplished.

Les boîtes quantiques (ou Quantum Dots en anglais - QD) sont une nouvelle génération de sondes polyvalentes pour la biologie, en particulier pour l’imagerie. Pour des applications de marquage des voies intra-cellulaires, les QDs peuvent être conjugués à des biomolécules telles que des acides nucléiques ou des protéines. En partant des travaux du LPEM portant sur le développement de ligands permettant la dispersion des QDs dans l’eau et leur fonctionnalisation, une nouvelle méthode de conjugaison de l'ADN sur les QDs a été développée dans cette thèse. Cette méthode utilise les motifs présents sur les polymères des QDs pour le greffage d'ADN. Les paramètres affectant cette réaction ont été étudiés et cette stratégie de couplage a été étendue à d'autres nanoparticules et biomolécules. En partant de ces QDs-ADN, des protéines modifiées ADN ont pu être attachées aux QDs en utilisant le principe d’hybridation de l’ADN. Les propriétés des conjugués ainsi générés ont été mises en évidence en utilisant la Transferrine (QD-ADN-Tf) et ces complexes ont été étudiés in vitro et in cellulo. Ces conjugués ont ensuite été utilisés pour le suivi de la dynamique des endosomes, exploitant ainsi pleinement le potentiel des QDs pour l’imagerie directe. Dans la dernière partie, des études supplémentaires sur les facteurs influençant la «performance biologique» des QDs ont été réalisées. Pour cela, une large gamme de ligands polymères développée par le groupe a été utilisée pour sonder l'interaction de la surface des QDs avec l'interface biologique. Des expériences biochimiques et cellulaires ont permis de démontrer que les QDs revêtus de divers polymères ont des comportements différents. / Quantum dots (QD) are new generation of versatile probes for biology, particularly for bioimaging. For specific applications, QDs are conjugated to biomolecules such as nucleic acid or proteins and subsequently targeted to unique intra-cellular pathways. Building upon the state-of-the-art ligands for water-dispersible QDs developed by the lab, a novel and highly generalizable method to conjugate DNA to QD is developed in this thesis. This method employs thiols present on polymers on QDs for conjugation to maleimide-functionalized DNA. Extensive characterization of parameters affecting this reaction is carried out and the strategy is extended to other nanoparticles and biomolecules. Following this, a novel method to conjugate proteins to QD via DNA hybridization is discussed. Using a model protein Transferrin (Tf), the unique properties of thus generated QD-DNA-Tf conjugates are studied in-vitro and in-cellulo. These conjugates are subsequently used for tracking endosomal dynamics for up-to 20 minutes, exploiting the fullest potential of QDs for live imaging. In the last part, additional studies on factors affecting the ‘biological performance’ of QDs are carried out. Using a range of highly adaptable polymeric ligands developed by the group, interactions of surface-modified QDs with the biological interface are probed. Systematic biochemical and cellular experiments demonstrate that QDs coated with zwitterionic polymers have superior antifouling properties compared to poly(ethylene glycol)-based polymers and stability in diverse biological contexts.

Pancreatic ductal adenocarcinoma (PDAC) has the poorest five-year survival rate of any cancer. Currently, there are no effective diagnostics or chemotherapeutics. Surgical resection is the only curative therapy. However, most patients experience recurrence due largely to challenges in assessing tumor margin status in the operating room. Molecular probes that selectively highlight pancreatic cancer tissue, having the potential to improve PDAC margin assessment intraoperatively, are urgently needed. In this work, a series of red and near-infrared fluorescent probes is reported. Two were found to distribute to normal pancreas following systemic administration. One selectively accumulates in genetically modified mouse models of PDAC, providing cancer-specific fluorescence. In contrast to the small molecule probes reported previously, it possesses inherent affinity for PDAC cells and tissue, and thus does not require conjugation to targeting agents. Moreover, the probe exhibits intracellular accumulation and enables visualization of four levels of structure including the whole organ, tissue, individual cells and subcellular organelles. It can thus promote new strategies for precision image-guided surgery, pancreatic cancer detection, the monitoring of therapeutic outcomes and basic research.

Transglutaminases (TGases) are a group of enzymes that catalyze the formation of an amide bond between the γ-carboxamide group of a glutamine residue and an amine donor, usually an ε-amino group of the lysine residue, leading to the formation of ε-(γ-glutamyl)lysine crosslinks. Owing to the roles that transglutaminases such as tissue transglutaminase (TG2) and Factor XIIIa (FXIIIa) have been found to play in a wide range of disease states, efforts have been directed towards the study of these proteins. The study of enzymes to better understand their function and mode of action is facilitated through the use of tools such as protein labelling, enzyme inhibition, and substrate analogue kinetic studies among others. Transition state analogues have been effective inhibitors in the study of enzyme activity. Sulfoxide inhibitors can efficiently mimic transition states leading to the tetrahedral intermediate of an acyl transfer reaction and we discuss the synthesis towards sulfoxide transition state analogue inhibitors of TG2 in chapter 2. Novel sulfoxide compounds were synthesized, though the desired target compounds proved difficult to isolate due to their instability. Fluorescent probes are effective in protein labelling as a means of discerning activity. This technique was applied in order to elucidate intracellular TG2 activity, which is a topic of controversy. To that end, the synthesis of a fluorescent, TG2-specific, cell permeable probe is discussed in chapter 3. However, preliminary in vivo results show that while the probe is cell permeable and fluorescent, it was not TG2-specific. Molecular modelling suggests that the hexa-arginine tag, designed to improve cell permeability, decreases the affinity of the probe for its intended target. Finally, FXIIIa has become a new addition to the study of transglutaminases in the Keillor group. Given our interest in this enzyme, we had three goals for this work as explained in chapter 4. Firstly, owing to the anticipated high demand for FXIIIa required for later experiments, our primary aim was the development of an optimized method for the expression and purification of recombinant FXIIIA. After evaluating different conditions for FXIIIA expression, the Studier auto-induction ZYP media1 at 20 °C for 24 h was found to provide the optimal conditions for the expression of recombinant GST-tagged FXIIIA, typically giving a total of 1.5 mg of protein/L of culture. Secondly, a variety of different peptides were synthesized and tested using a glutamate dehydrogenase (GDH)-based assay to identify a high affinity sequence for a substrate of FXIIIa. The two peptides with the highest affinity for FXIIIa were Ac-DQMMMAF-OH and Ac-DQMML-OH. Testing with TG2 displayed negligible reactivity, confirming their use as orthogonal peptides, results reinforced by modelling studies of the peptides with both FXIIIa and TG2. This discovery represents the first time peptides orthogonal to TG2 with affinity for FXIIIa have been kinetically characterized with both transglutaminase enzymes. Lastly, our work towards a fluorogenic activity assay by incorporating a coumarin ester through attachment to a glutamic acid residue into a peptide sequence recognized by FXIIIa, will be discussed.

Molecular recognition is essential to all biological interactions and processes. Knowledge of the structural basis of recognition offers a powerful mechanism for understanding, predicting and controlling the behaviour of biological systems. In this thesis, we present, firstly a computational and crystallographic analysis of molecular recognition in protein-ligand systems; and secondly, progress towards the synthesis of a fluorescent probe for calcium ion recognition. Class I phosphoinositide 3-kinases (PI3Ks), in particular PI3Kγ, have long been considered promising drug targets for the treatment of inflammatory and autoimmune disorders. As a step towards improved understanding of PI3K binding preferences, we examine the basis on which PI3Kγ distinguishes γ-selective inhibitors AS-605240 and AS-604850, with a ~30-fold preference for the former. Interestingly, despite the chemical similarity of the two ligands, the X-ray structures for their PI3Kγ complexes exhibit the molecules in different conformers, s-cis for AS-604850 and s-trans for AS-605240. Here, we re-examine the PI3Kγ/AS-605240 crystallographic data and find that not only is a s-cis conformation possible but in fact it has a much higher occupancy (87%) than the originally modelled s-trans isomer (13%). Subsequently, to account for the isomeric complexities presented by the ligands, we perform 140 ns MD simulations of the four PI3Kγ complexes in explicit solvent: this reveals similar conformational flexibility at the active site for all systems. Yet, the conformations sampled by the s-cis isomers are more consistent with the conformations reported by the X-ray crystal structures. Subsequent energetic analysis was performed incorporating ensemble-averaging and desolvation effects via the Poisson-Boltzmann continuum solvent model. For both inhibitors the s-cis isomers are predicted to be the most favourable conformations. Additionally, the results indicate a preference for AS-605240, as observed experimentally. The molecular basis for this preference is discussed, together with a comparison of molecular mechanical and quantum chemical treatments of the key ligand-Val882 interaction. This study provides structural, dynamical and energetic insights into the subtle basis of molecular recognition by PI3Kγ.Fluorescent probes have evolved into an extremely useful tool for the detection of calcium in biological systems. Benzothiazole derivatives BTC, and its iminocoumarin analogue BTIC, are two low affinity calcium indicators featuring many desirable properties for cellular calcium measurement. In an effort to produce fluorophores that can be chemically conjugated with a screening protein, such as Green Fluorescent Protein (GFP), we aimed to derivatise BTC and BTIC. Two synthetic approaches towards the synthesis of these potential fluorescent probes are outlined.

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2017-07-13T14:09:49Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Zenaide S Monte - Tese Doutorado - Defesa 15-jul-2016.pdf: 10509605 bytes, checksum: 9a625f96607c0ccae6d58b896ba38772 (MD5) / Made available in DSpace on 2017-07-13T14:09:49Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Zenaide S Monte - Tese Doutorado - Defesa 15-jul-2016.pdf: 10509605 bytes, checksum: 9a625f96607c0ccae6d58b896ba38772 (MD5) Previous issue date: 2016-07-15 / CAPES / Compostos heterocíclicos do tipo pirimidina são conhecidos pela enorme riqueza de seus potenciais biológicos e farmacológicos. Numerosas reações de heterociclização que permitem a obtenção dessa classe de compostos são igualmente reconhecidas, devido à diversidade de atividades e do conhecimento prévio de inúmeras viabilidades sintéticas. As modificações estruturais obtidas na busca da otimização das rotas sintéticas conferem às novas moléculas diferentes propriedades físicas e alteram a reatividade das moléculas, acarretando em mudanças na distribuição nas células e nos tecidos. Essas discretas modificações estruturais podem revelar efeitos biológicos que haviam estado latentes ou eclipsados pelos efeitos colaterais do composto protótipo. Sendo assim, o presente trabalho apresenta a síntese por método convencional dos derivados da pirimidina 3a-q e 5o-q. Estes compostos foram avaliados quanto às propriedades duais: Antimicrobiana e Fotoluminescência, estas apresentaram resultados promissores, podem atuar como boas sondas fluorescentes. Foram realizados também estudos Espectrofotométricos em diferentes solventes além de determinarmos o Cálculo do Orbital Molecular de Fronteira nesta série. Realizou-se também a nanoencapsulação em lipossomas para o composto 3o. Obtivemos também p-arilamidinas 3a-j por método convencional e avaliamos as propriedades Antimicrobiana e Citotóxica, as quais apresentaram resultados significativos. Realizamos a síntese dos derivados pirimidínicos 3a-f e 6a-f pelo método em Irradiação em micro-ondas, em fase sólida e em solução, respectivamente. Estudamos também para estes as propriedades Antimicrobiana e Antioxidante, cujos os resultados foram satisfatórios. Foram obtidos bons rendimentos para todos os compostos obtidos. Um estudo inédito de RMN bidimensional, COSY, HSQC e HMBC foram aplicados às pirimidinas foi realizado, proporcionando a caracterização estrutural destes compostos. Os resultados obtidos apresentaram significativa potencialidades biológicas, farmacológicas e fotofísicas. / Heterocyclic compounds of pyrimidine are known for rich biological and pharmacological potential. A number of heterociclic reactions that enable the obtention of this class of compounds are also recognized, due to the diversity of activities and prior knowledge of their various synthetic viabilities. The structural modifications obtained in search for the best synthetic routes confered different physical properties on the new molecules and altered the reactivity of the molecules, resulting in changes in the distribution in cells and tissues. These discrete structural changes may reveal biological effects that may have been latent or eclipsed by the side effects of the compound prototype. This work presents the synthesis by conventional method of derivatives from pyrimidine 3a-q and 5o-q. These compounds were evaluated for dual properties: antimicrobial and photoluminescence. They showed promising results can act as fluorescent probes. Spectroscopic studies were carried out with different solvents and the Frontier Molecular Orbital calculation for this series was determined. Nanoencapsulation of liposomes for the compound 3o was prepared. The conventional method was used to obtain 3a-j p-arilamidinas. Results were significant for the antimicrobial and cytotoxic properties. Finally, the synthesis of pyrimidines derivatives 3a-f and 6a-f by a new method, solid phase micro-wave and in solution, respectively was carried out. We have studied both the Antimicrobial and Antioxidant properties with satisfactory results. Good yields were obtained for all compounds obtained. New studies of two-dimensional NMR, COSY, HSQC and HMBC were performed besides the characterization of the compounds by standard methods. The results show that the compounds obtained have great biological, pharmacological potential and Photophysical.