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Some properties of soluble chromium complexions containing coordinated aliphatic acids have been studied. The work falls naturally into two sections. In the first, the coordination of a series of ⊄, β and⊁amino acids by chromium chloride has been studied by physical methods. The tanning action of chromium chloride in the presence of these amino acids has also been studied. The absorption spectra of the complexes were similar to those reported previously for trivalent chromium solutions, having two pronounced maxima in the visible region. From the variations in these absorption maxima, it is suggested that the absorption maximum in the 580 m u region is influenced by coordination of the chromium with the ligand, while the maximum in the 420 m u region is also affected by the olation of the basic chromium salts. The spectrophotometric evidence indicates that raising the pH or the concentration of the ligand in the solution increases the amount of coordination, and further, that the tendency for coordination increases as the hydrocarbon chain separating the carboxyl and amino groups becomes longer. This suggests that tho stability of the complex is not dependent on chelate ring formation, but is influenced by the pK₁ value of the carboxyl group of the . ligand. Potentiometric titrations support the hypothesis that only the carboxyl group is coordinated, to an extent depending on its pK₁ value, since the curves have shown that the amino group is still free to titrate. Paper electrophoresis has shown that all the complexes prepared were cationic, indicating that the amino acids were coordinated as dipolar ions. The tanning action of the masked chromium solutions has confirmed the deductions made from the physical measurements. Increasing the amount of amino acid added to the solution lowered the chromium fixation and the hydrothermal stability of the leather, and further, that for solutions at the same pH containing the same amount of masking agent, tanning action was least for the ⊁ amino acid and greatest for the ⊄ amino acids. Comparison of the present data with the corresponding results obtained with chrome alum solutions showed that coordination of the amino acids was greater in the case of the chromium chloride solutions. The second section of the experimental work was an investigation of the coordination of substituted acetic and propionic acids by chromium chloride and chromium sulphate. Spectrophotometric and potentiometric methods were applied and the various solutions were also used in miniature tanning experiments. Certain difficulties were encountered in the preparation of some of the complexes, and it was not possible to carry the work to a point where conclusive results could be obtained. Nevertheless, the work reported suggests that chelate ring formation occurs in the coordination of hydroxy-carboxylic acids, resulting in exceptionally high stability of the complex. In the case of the other ligands, containing amino, chloro and bromo groups, as well as with acetic and propionic acids, the results suggest that coordination involves the carboxyl group only, and that the pY value of this group is an important factor determining the stability of the complexes.

Les héparanes sulfates (HS) sont synthétisés à partir d’un précurseur non sulfaté, formé de la répétition du disaccharide [GlcUA ß1,4 GlcNAc]. Ce précurseur est ensuite modifié par des enzymes de maturation, N-déacétylase/N-sulfotransférases (NDSTs), O-sulfotransférases (OSTs) et C5-épimérase. Ces enzymes, dont l’expression est dépendante du type cellulaire, possèdent des activités et des spécificités de substrat différentes, ce qui confère une grande hétérogénéité structurale aux HS et offre un large éventail de motifs de fixation pour les protéines. Il est clairement établi que les protéoglycanes à chaînes HS régulent la fixation et l'activité de nombreux facteurs inflammatoires. En revanche, peu d'informations sont disponibles sur la nature de leurs motifs HS de fixation. L’objectif de ces travaux a été de relier les variations d'expression des glucosaminyl sulfotransférases à la génération de motifs HS spécialisés dans la fixation des facteurs inflammatoires / Heparan sulfate (HS) are synthesized from a non-sulfated precursor, formed by the repetition of the disaccharide unit [GlcUA ß1,4 GlcNAc]. This precursor is subsequently modified by a set of enzymes of maturation, N-deacetylase/N-sulfotransferases (NDSTs), O-sulfotransferases (OSTs) and C5-epimerase. These enzymes, whose expression is dependent on cell type, exhibit fine differences in activity and substrate specificity, which confer a large structural heterogeneity in HS species and offer a plethora of binding sites for proteins. It is now well established that HS proteoglycans regulate the binding and activity of a number of inflammatory factors. However, little is known about the structural features of HS sequences involved in these interactions. The aim of these works was to correlate the cell-type specific expression of HS biosynthetic enzymes to the generation of specialized HS motifs with binding properties for inflammatory factors.

M.S.

Akademisk arhandling--Göteborg. / Extra t.p. with thesis statement inserted. Bibliography: p. [38].

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Ces vingt dernières années, les batteries lithium-ion sont devenues dominantes parmi les technologies de stockage d’énergie électrique. Selon les applications, ces batteries (ou les matériaux qui la constituent) doivent présenter différentes spécificités: notamment une grande densité d’énergie, un bas coût, des contraintes de sécurité et de durabilité. Dans ce but, le développement de nouveaux matériaux d’électrode est indispensable. Nous nous sommes engagés, dans cette thèse, dans la synthèse des nouveaux composés polyanioniques à base de sulfates et fluorosulfates comme matériaux d’électrodes positives. Au cours de notre étude, nous avons synthétisé un nouveau polymorphe de KFeSO4F, de symétrie monoclinique, dont nous avons déterminé la structure en combinant la diffraction des rayons X et des neutrons sur poudre. Il est possible d’extraire électrochimiquement K+ de KFeSO4F et de réinsérer Li+ dans cette nouvelle matrice «FeSO4F» à un potentiel moyen de 3.7 V vs. Li+/Li0. Ensuite, nous nous sommes penchés vers des matériaux dépourvus de fluor et nous avons découvert une nouvelle phase Li2Fe(SO4)2 orthorhombique, qui présente des propriétés électrochimiques intéressantes avec un potentiel de 3.73 et 3.85 V vs. Li+/Li0 et une bonne cyclabilité. Nous avons également étudié le composé langbeinite K2Fe2(SO4)3 pour son aptitude à intercaler Li+ une fois le K+ extrait, avec cependant peu de succès. Néanmoins, en examinant d’autres phases langbeinites K2M2(SO4)3 avec M=métaux de transition 3d, nous avons découvert un nouveau composé K2Cu2(SO4)3, qui cristallise dans une structure différente de celle des langbeinites. Enfin, nous n’avons pas seulement étudié ces nouveaux matériaux pour leurs propriétés électrochimiques mais nous avons été également capables de révéler d’autres caractéristiques physiques intéressantes, notamment magnétiques. Les composés Li2Fe(SO4)2 orthorhombique et KFeSO4F monoclinique s’ordonnent antiferromagnétiquement à longue distance et leur structure magnétique autorise un couplage magnéto-électrique. / Lithium-ion batteries (LIBs) have become the dominating electrical energy storage technology in the last two decades. However, depending on their applications, LIBs need to fulfill several requirements such as high energy density, low-cost, safety and sustainability. This calls for the development of new electrode materials. Focusing on the cathode side, we embarked on the synthesis of novel sulfate- and fluorosulfate-based polyanionic compounds. During the course of our study, we discovered a monoclinic KFeSO4F polymorph, whose structure was determined via combined X-ray and neutron powder diffraction. We could electrochemically extract K+ and reinsert Li+ into this new polymorphic “FeSO4F” matrix at an average potential of 3.7 V vs. Li+/Li0. We then turned towards fluorine-free materials and synthesized a new orthorhombic Li2Fe(SO4)2 phase, which presents appealing electrochemical properties in terms of working potential (3.73 and 3.85 V vs. Li+/Li0) and cycling stability. In a next step, we tested langbeinite K2Fe2(SO4)3 for its aptitude to intercalate Li+ once K+ is extracted, with however little success. Nevertheless, exploring other langbeinite K2M2(SO4)3 phases (M=3d transition metal), we discovered a new K2Cu2(SO4)3 compound, which crystallizes in an orthorhombic structure distinct from the langbeinite one. Finally, we investigated these compounds not only for their electrochemistry, but we were also able to demonstrate other interesting physical properties, namely magnetic features. Orthorhombic Li2Fe(SO4)2 and monoclinic KFeSO4F both present a long-range antiferromagnetic spin ordering whose symmetry allows a magnetoelectric effect.

Tissue inhibitor of metalloproteinase-3 (TIMP-3) is a protein with multiple functions that include regulating the turnover of the extracellular matrix (ECM) by inhibiting members of the metzincin family. Extracellular levels of soluble TIMP-3 are low, reflecting its binding to components of the ECM including sulfated glycosaminoglycans (SGAGs) and its endocytosis by low density lipoprotein receptor-related protein 1. Because TIMP-3 inhibits ECM-degrading enzymes, the ability of SGAG mimetics to elevate extracellular concentrations of TIMP3 is of interest for osteoarthritis treatment. However, previous studies of such interactions have utilized immobilized forms of the protein or ligands. Here we have quantified the thermodynamics of the interactions of the inhibitory domain of TIMP-3 with chondroitin sulfate (CS), pentosan polysulfate (PPS) and suramin in solution using isothermal titration calorimetry. All three interactions are driven by a (favorable) negative enthalpy ychange combined with an unfavorable decrease in entropy. The heat capacity change (ΔCp) for the interaction of N-TIMP-3 with CS, PPS, or suramin is essentially zero, indicating an insignificant contribution from the hydrophobic effect. Based on the effects of ionic strength on the interaction of N-TIMP-3 with suramin, their interaction appears to be driven by electrostatic interactions. Modeling supports the view that the negatively charged sulfates of CS, PPS, and suramin interact with a cationic region on N-TIMP-3 that includes Lys -26, -27, -30, and -possibly 76 on the opposite face of TIMP-3 from its reactive site for metalloproteases. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2019. / FAU Electronic Theses and Dissertations Collection

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