No abstract

The use of a low-cost benchtop time-domain NMR (TD-NMR) spectrometer to monitor copper electrodeposition in situ is presented. The measurements are based on the strong linear correlation between the concentration of paramagnetic ions and the transverse relaxation rates (R(2)) of the solvent protons. Two electrochemical NMR (EC-NMR) cells were constructed and applied to monitor the Cu(2+) concentration during the electrodeposition reaction. The results show that TD-NMR relaxometry using the Carr-Purcell-Meiboom-Gill pulse sequence can be a very fast, simple, and efficient technique to monitor, in real time, the variation in the Cu(2+) concentration during an electrodeposition reaction. This methodology can also be applied to monitor the electrodeposition of other paramagnetic ions, such as Ni(2+) and Cr(3+), which are commonly used in electroplating.

Metabolites present in liver provide important clues regarding the physiological state of an organism. The aim of this work was to evaluate a protocol for high-throughput NMR-based analysis of polar and non-polar metabolites from a small quantity of liver tissue. We extracted the tissue with a methanol/chloroform/water mixture and isolated the polar metabolites from the methanol/water layer and the non-polar metabolites from the chloroform layer. Following drying, we re-solubilized the fractions for analysis with a 600 MHz NMR spectrometer equipped with a 1.7 mm cryogenic probe. In order to evaluate the feasibility of this protocol for metabolomics studies, we analyzed the metabolic profile of livers from house sparrow (Passer domesticus) nestlings raised on two different diets: livers from 10 nestlings raised on a high protein diet (HP) for 4 d and livers from 12 nestlings raised on the HP diet for 3 d and then switched to a high carbohydrate diet (HC) for 1 d. The protocol enabled the detection of 52 polar and nine non-polar metabolites in 1H NMR spectra of the extracts. We analyzed the lipophilic metabolites by one-way ANOVA to assess statistically significant concentration differences between the two groups. The results of our studies demonstrate that the protocol described here can be exploited for high-throughput screening of small quantities of liver tissue (approx. 100 mg wet mass) obtainable from small animals.

Endogenous production of α-dicarbonyls by lactic acid bacteria can influence the quality and consistency of fermented foods and beverages. Methylglyoxal (MG) in Parmesan cheese can contribute toward undesired browning during low temperature ripening and storage conditions, leading to the economic depreciation of affected cheeses. We demonstrate the effects of exogenously added MG on browning and volatile formation using a Parmesan cheese extract (PCE). To determine the influence of Lactobacillus on α-dicarbonyls, strains were screened for their ability to modulate concentrations of MG, glyoxal, and diacetyl in PCE. It was found that a major metabolic pathway of MG in Lactobacillus is a thiol-independent reduction, whereby MG is partially or fully reduced to acetol and 1,2-propanediol, respectively. The majority of lactobacilli grown in PCE accumulated the intermediate acetol, whereas Lactobacillus brevis 367 formed exclusively 1,2-propanediol and Lactobacillus fermentum 14931 formed both metabolites. In addition, we determined the inherent tolerance to bacteriostatic concentrations of MG among lactobacilli grown in rich media. It was found that L. brevis 367 reduces MG exclusively to 1,2-propanediol, which correlates to both its ability to significantly decrease MG concentrations in PCE, as well as its significantly higher tolerance to MG, in comparison to other lactobacilli screened. These findings have broader implications toward lactobacilli as a viable solution for reducing MG-mediated browning of Parmesan cheese.

Breast cancer metastasis occurs via blood and lymphatic vessels. Breast cancer cells ‘educate’ lymphatic endothelial cells (LECs) to support tumor vascularization and growth. However, despite known metabolic alterations in breast cancer, it remains unclear how lymphatic endothelial cell metabolism is altered in the tumor microenvironment and its effect in lymphangiogenic signaling in LECs. We analyzed metabolites inside LECs in co-culture with MCF-7, MDA-MB-231, and SK-BR-3 breast cancer cell lines using $$^1\hbox {H}$$ 1 H nuclear magnetic resonance (NMR) metabolomics, Seahorse, and the spatial distribution of metabolic co-enzymes using optical redox ratio imaging to describe breast cancer-LEC metabolic crosstalk. LECs co-cultured with breast cancer cells exhibited cell-line dependent altered metabolic profiles, including significant changes in lactate concentration in breast cancer co-culture. Cell metabolic phenotype analysis using Seahorse showed LECs in co-culture exhibited reduced mitochondrial respiration, increased reliance on glycolysis and reduced metabolic flexibility. Optical redox ratio measurements revealed reduced NAD(P)H levels in LECs potentially due to increased NAD(P)H utilization to maintain redox homeostasis. $$^{13}\hbox {C}$$ 13 C -labeled glucose experiments did not reveal lactate shuttling into LECs from breast cancer cells, yet showed other $$^{13}\hbox {C}$$ 13 C signals in LECs suggesting internalized metabolites and metabolic exchange between the two cell types. We also determined that breast cancer co-culture stimulated lymphangiogenic signaling in LECs, yet activation was not stimulated by lactate alone. Increased lymphangiogenic signaling suggests paracrine signaling between LECs and breast cancer cells which could have a pro-metastatic role.

Methods for maintaining membrane proteins in their native state after removal from the lipid bilayer are essential for the study of this important class of biomacromolecules. Common solubilization strategies range from the use of detergents to more complex systems that involve a polypeptide working in concert with lipids or detergents, such as nanodiscs, picodiscs, and peptidiscs, in which an engineered protein or synthetic peptide surrounds the membrane protein along with a lipid sheath. Picodiscs employ the protein saposin A, which naturally functions to facilitate lipid degradation in the lysozome. Saposin A–amphiphile complexes therefore tend to be most stable at acidic pH, which is not optimal for most membrane protein applications. In search of new picodisc assemblies, we have explored pairings of saposin A or other saposin proteins with a range of detergents, and we have identified a number of combinations that spontaneously co-assemble at neutral pH. The resulting picodiscs are stable for weeks and have been characterized by size-exclusion chromatography, native mass spectrometry, and small angle X-ray scattering. The new assemblies are formed by double-tail detergents rather than more traditional single-tail detergents; the double-tail detergents can be seen as structurally intermediate between single-tail detergents and common lipids. In addition to saposin A, an engineered variant of saposin B (designated saposin BW) forms picodisc assemblies. These findings provide a framework for future efforts to solubilize membrane proteins with multiple picodisc systems that were previously unknown.

À Deus, por todas as oportunidades e auxílios concedidos. À minha mãe Celina e à minha irmã Joana, por sempre me ajudarem e estarem presentes em cada etapa, sendo apoio indispensável para realização deste projeto. Ao meu avô, pelo incentivo e amor. Ao Matthew, Sheila e Jeff por me receberem em sua família e por me apoiarem desde o momento que entraram em minha vida. Ao Dr. Luiz Alberto Colnago, por toda a paciência, humor e dedicação nos mais de 10 anos de orientação e amizade. Sem ele, eu não estaria aqui. Aos colegas do grupo de RMN da EMBRAPA: André, Bruna, Carlos, Cirlei, Dani, Diego, Luiz, Roberta, Rodrigo, Tati e Tiago, por tornar os dias de trabalho alegres. Em especial à doutora Maria Gabriela Aparecida Carosio pelos anos de amizade, auxílio e incentivo. Por ter me ajudado nos dias bons e ruins e por ter lido e relido esta tese, oferecendo sugestões de melhoria. Ao Dr. Otavio Henrique Thiemann pela coorientação e por ceder o espaço e material do LBEst para cultivo de Leishmania. Aos colegas de grupo, que me ensinaram quando eu nada sabia sobre cultivo de protozoários, em especial ao pessoal da Sala de Cultura: Ana Laura, Érika, Ivan, Natielli, Thomás e Tulio. Ao NMRFAM em Madison-WI pelo ano incrível de experiências e aprendizado. Ao Dr. John L. Markley por ter me recebido e aos doutores W. Milo Westler, Mark Anderson, David Aceti, Hamid Eghbalnia e a doutora Fariba Fathi pela troca de experiências e discussões sobre RMN e metabolômica.

À minha mãe Celina, porto seguro da minha existência, que está e sempre estará por mim.À minha irmã Joana, por me ajudar quando preciso e por fazer meus dias mais alegres.Ao meu avô, figura paterna e estrela guia dos meus passos.Ao meu pai e demais familiares que embora distantes, estão sempre próximos.Ao Dr. Luiz Alberto Colnago, por toda a paciência, humor e dedicação na orientação e amizade. Sem ele, nada disso seria possível.Aos amigos, sempre presentes em minha vida, sem os quais não seria nada: Gai, Pri, Gabi, Maya, Dri, Ani, Marina, Tonton, Thinho, Sasun, Ju, Tassi, Sá.Aos novos amigos Henry, Michel, Pedro.Aos colegas e amigos de grupo, laboratório e sala: Alexandra, André, Cabeça, Carol, Clarisse, Dani, Fabi, Fabíola, Lucinéia, Maiara, Matheus, Poli, Rafa, Roberta, Tati e Tiago, por fazer os dias de trabalho alegres.À Luiza por toda a ajuda e assistência, em vários momentos da pesquisa.À todos aqueles que leram, releram e leram de novo a dissertação, contribuindo significativamente para que ela pudesse ser finalizada.Aos amigos Luis, Vivi, Camila, Ana Paula, Edison, Keithy, Thamara, Lucas, Doni, Vânia, Tais e Rosana, pela convivência em todos estes anos, certamente enobrecedora. Também ao Rafa, Aninha, Gábi, Vivi, Lê e Gi. À Edna, Maris, Pazu, Dolores, Jacy, Yára, Iara, Washington, Jô, Terezinha, Cláudio, pessoal do PC pela convivência e aprendizagem. Também ao Zé, Antônio, Henrique, Luis Roberto pelas conversas e conselhos constantes.Ao Prof. Dr. Lúcio Leonel Barbosa, por iniciar o trabalho de eletroquímica-RMN no grupo de pesquisa.A todos os professores que contribuíram de alguma forma para minha formação científica.À Embrapa Instrumentação pela infra-estrutura dos laboratórios e pelo bom ambiente para o desenvolvimento da pesquisa de mestrado. AbstractThe study of ionic solutions is of great importance to analytical chemistry. In NMR, a significant number of researchers devote themselves to the understanding of the role that paramagnetic ions have on longitudinal (T 1 ) and transverse (T 2 ) relaxation times. However, most of the papers published until today have studied this influences on T 1 , which is whatsoever more complicated to measure than T 2 . Therefore, we applied we applied the time domain NMR (TD-NMR) transverse relaxometry to study paramagnetic ions in aqueous interesting. To the in situ study two electrochemical cells were built and tested, cyclic voltammetry and amperometric deposition were made. The best result was for iron, followed by copper. Manganese electrodeposition wasn't observed.