A tridentate diphenolate phosphine ligand H2[OPO] (bis(3,5-di-tert-butyl-2-hydroxyphenyl)phenylphosphine) has been synthesized in high yield. Treatment of H2[OPO] with Ti(OEt)4 in toluene at room temperature produced reddish orange crystalline Ti[OPO]2. The bis-ligand complex Ti[OPO]2 also be obtained from the in situ lithiation of H2[OPO] in THF or toluene followed by addition of TiCl4(THF)2. The reactions of MCl2[N(SiMe3)2]2 (M = Zr, Hf) with H2[OPO] in pentane at room temperature generated cleanly [OPO]2Zr(H2O) and [OPO]2Hf(H2O), respectively, in high yield. Treatment of TiCl4(THF)2 with Ti[OPO]2 in toluene afforded [OPO]TiCl2(THF). The solution and solid-state structures of Ti[OPO]2, [OPO]TiCl2(THF), [OPO]2Zr(H2O) and [OPO]2Hf(H2O) were studied by multinuclear NMR spectroscopy and X-ray crystallography. lithiation of H2[OPO] with n-BuLi in DME solution afforded [OPO]Li2(DME)2. The metathetical reactions of H2[OPO] with NaH or KH in DME solutions, respectively, produced the corresponding complexes [OPO]Na2(DME)2 and {[OPO]K2(DME)2}2. Both [OPO]Li2(DME)2 and [OPO]Na2(DME)2 are highly active catalysts for ring-opening polymerization of caprolactone. A series of tetravalent tin complexes [OPO]SnX2 (X = Cl, Me, n-Bu) also be obtained from the in situ lithiation of H2[OPO] in THF followed by addition of SnCl2X2. A divalent tin complexe [OPO]Sn also be obtained by analogous way from the in situ lithiation of H2[OPO] in pentane followed by addition of SnCl2.

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Hemilabile ligands attracted much attention in past thirty years because they were effectively utilized in the field of coordination chemistry and homogenous catalysis. We have synthesized four tridentate iminophosphine ligands (o-Ph2P(C6H4)-C(H)=N-(CH2)n-R, n = 2, R = SnBu, LPNS1; n = 3, R = SMe, LPNS2; n = 3, R = OMe, LPNO3; and n = 3, R = NMe2, LPNN4) and one tridentate aminophosphine ligand (o-Ph2P(C6H4)CH2N(H)(CH2)3NMe2, LPNHN5) in this work. The structures of the iminophosphine copper(I) complexes were determined by the carbon-chain length between imino-nitrogen and third donor atom, the coordination ability of the third donor atom, and the nature of the anions (i.e. its donor ability and atomic radius). An unexpected tetranuclear copper(I) iodide complex [(CuI)2(LPNN4)]2 (16) was obtained due to the larger atomic radius of iodide ion. The ligand LPNN4 displayed versatile coordination behavior after complexing with some late transition metals such as Pd(II), Ag(I), Zn(II), Cd(II). These tridentate ligands may act as PN-chelator or PNE-chelator (E = S, N¡¦). Both chelating and bridging modes were observed at the same time in Cu(I) and Ag(I) complexes. In Zn(II) complex, however, chelating by LPNN4 chelated only occurred through its N donor atoms. In term of the reactivity study of these complexes, we found that the complex [Cu(LPNN4)(CH3CN)0.2](BF4) (17) would successful react with Na(SCN), NaN3, and PhCCH/KOH to generate corresponding substitution products. However when reacted with PhCCC(O)OH/KOH, copper complexes bearing LPNN4 could not give the corresponding substituted carboxylate copper(I) product and gave the complex [Cu(CCPh)(LPNN4)]2 (18) via auto-decarboxylation instead.

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Efficient separation of target protein from impurities is crucial in bioseparation for large scale production and purity of the target protein. Two separation process approaches were considered in this study. The first approach focused on identifying major impurity and optimization of solution properties for target protein purification. The second approach consisted of designing an adsorbent that interacted specifically with the target molecule. The first study included modification of protein solution properties (pH, ionic strength, buffer ions) in order to maximize lysozyme purification by a strong cation exchange resin. The interaction of phytic acid, a major impurity, present in transgenic rice extracts, that contributes to decreased lysozyme adsorption capacity on SP Sepharose was evaluated. The target protein was lysozyme, which is used in a purified form as a baby formula additive to reduce gastrointestinal tract infections. At constant ionic strength, lysozyme in pH 4.5 acetate buffer had a higher binding capacity and stronger binding strength than at pH 6.0. Lysozyme in sodium phosphate buffer of pH 6.0 exhibited lower adsorption capacity than in pH 6 Tris buffer. Binding capacity and strength were significantly affected by phytic acid in all studies buffers. The second study consisted of surface modification of microfiltration membranes for protein purification and separation and reduces fouling. This study describes adsorption and fouling of chemically modified microfiltration membranes with bovine serum albumin (BSA) and immunoglobulin G (IgG). Least fouling resulted with polyethylene glycol (PEG) membranes when BSA protein was used. Amine-functionalized membranes showed specific interaction with BSA. There was multi-layer deposition of IgG on amine-functionalized membrane. G3 membrane synthesized to selectively bind IgG seemed a noble option to separate IgG from a protein mixture.

Diss.--Turku--Å̊bo Akademi University, 2003. / Contient cinq articles du même auteur publiés dans des revues scientifiques. Bibliogr. p. 35-43.

Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references.

Zugl.: Aachen, Techn. Hochsch., Diss., 2009

Ligand-induced internalisation and subsequent downregulation of receptor tyrosine kinases (RTKs) serve to determine biological outputs of their signalling. Intrinsically kinase-deficient RTKs control a variety of biological responses, however, the mechanism of their downregulation is not well understood and its analysis is focused exclusively on the ErbB3 receptor. The Eph group of RTKs is represented by the EphA and EphB subclasses. Each bears one kinase-inactive member, EphA10 and EphB6, respectively, suggesting an important role for these molecules in the Eph signalling network. While EphB6 effects on cell behaviour have been assessed, the mechanism of its downregulation remains elusive. Our work reveals that EphB6 and its kinase-active relative, and signaling partner, EphB4, are downregulated in a similar manner in response to their common ligand, ephrin-B2. Following stimulation, both receptors are internalised through clathrin-coated pits and are degraded in lysosomes. Their targeting for lysosomal degradation relies on the activity of an early endosome regulator, the Rab5 GTPase, as this process is inhibited in the presence of a Rab5 dominant-negative variant. EphB6 also interacts with the Hsp90 chaperone and EphB6 downregulation is preceded by their rapid dissociation. Moreover, the inhibition of Hsp90 results in EphB6 degradation, mimicking its ligand-induced downregulation. These processes appear to rely on overlapping mechanisms, since Hsp90 inhibition does not significantly enhance ligand-induced EphB6 elimination. Taken together, our observations define a novel mechanism for intrinsically kinase-deficient RTK downregulation and support an intriguing model, where Hsp90 dissociation acts as a trigger for ligand-induced receptor removal.

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy