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Tesi sul tema "Macromolecular"
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1
Mohsin, Huma. "Macromolecular radiopharmaceuticals /". free to MU campus, to others for purchase, 2004. http://wwwlib.umi.com/cr/mo/fullcit?p3164529.
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2
Kim, Michael F. "Modeling macromolecular assemblies". Diss., Search in ProQuest Dissertations & Theses. UC Only, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3324618.
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3
Walter, Thomas S. "Methodology for macromolecular crystallization". Thesis, University of Oxford, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.542989.
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4
Muthukumar, Murugappan. "Macromolecular translocation through nanopores". Diffusion fundamentals 16 (2011) 6, S. 1, 2011. https://ul.qucosa.de/id/qucosa%3A13734.
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5
Katsimitsoulia, Zoe. "Macromolecular studies for bionanotechnology". Thesis, University of Oxford, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.559772.
Testo completoAbstract (sommario):
Conventional computational methods available today for studying macromolecules and their complexes are limited to simulating short time frames and are insufficient to study processes of interest related to their function that usually occur In nature on longer time scales. Alternative methods that extend our capabilities continue to be proposed, and most often involve some kind of reduction In complexity or representation in order to simulate these biological processes on longer time and length scales. The ability to investigate through simulation the structural and functional properties of protein macromolecular complexes IS of particular importance in the field of bionanotechnology, whose goal IS to harness nanoscale devices made from or inspired by biological counterparts. Clearly then, methods are needed that can capture the large changes seen In macromoleculat assemblies to elucidate important principles of their structure and function and apply these to the nanomachines envisaged in bionanotechnology. At the forefront of this field lie the nanomotors, whose biological counterparts, the molecular protein motors, are used in cells to drive a host of essential processes with an amazing degree of efficiency and precision. The work in this thesis describes the development of a hierarchic modeling paradigm applied toward simulating the processi ve movement of the molecular myos m motor protein along an actin filament track. In the hierarchic model, three different levels of protein structure resolution are represented, with the level of detail changing according to the degree of interaction among the molecules, the integrity of which is maintained using a tree of spatially organized bounding volumes. Although applied to an acto-myosin system, the hierarchic framework is general enough so that it may easily be adapted to a number of other biomolecular systems of interest within the bionanotechnology field.
6
Muthukumar, Murugappan. "Macromolecular translocation through nanopores". Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-184573.
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7
Van, De Walle Matthias. "Continuous photoflow for macromolecular design". Thesis, Queensland University of Technology, 2021. https://eprints.qut.edu.au/208293/1/Matthias_Van%20De%20Walle_Thesis.pdf.
Testo completoAbstract (sommario):
The current thesis critically advances the synthesis of precision macromolecular structures via photochemical approaches. The work examines the use of continuous photoflow setups to facilitate scalable synthesis of various polymeric architectures, and helps to overcome limitations that hinder photochemistry to be incorporated more frequently into industrial processes. This thesis demonstrates the flexibility and versatility of continuous photoflow and its potential to be developed further, to exceed currently existing photochemical procedures based on traditional batch approaches.
8
Zhang, Weizhe, e 張蔚哲. "Development of macromolecular phasing methods". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/206741.
Testo completoAbstract (sommario):
X-ray crystallography is a powerful method in determining the structure of both small molecules and macromolecules and is now routinely applied in many scientific fields. However, to apply this method, there is an unavoidable problem to tackle: the Phase Problem, which arises because the phases of a scattered x-ray cannot be measured in diffraction experiment and the original structure cannot be retrieved only with the measurable amplitudes. This thesis presents two approaches in the development of macromolecular phasing methods.
One approach presented here utilizes molecular envelope of NMR structures for molecular replacement (MR) phasing with the program FSEARCH at low resolution (about 6 Å). X-ray crystallography and NMR are complementary tools in structural biology. However, it is often difficult to use NMR structures as search models in MR to phase crystallographic data. For this purpose, in our study, several targets with both crystallographic and NMR structures available have been tested. The test protocol involves four steps: (1) Model preparation, NMR structures were processed into averaged polyalanine model, and centroid NMR models have also been tested; (2) Six-dimensional low resolution search were carried out by FSEARCH to find the best match between observed and calculated structure factors; (3) Apply the solution (4) Model building and refinement. In our tests, FSEARCH was able to find the correct translation and orientation of the search model in the crystallographic unit cell, while conventional MR procedures were unsuccessful.
The other approach presented in this thesis is protein complex structure completion using IPCAS (Iterative Protein Crystal structure Automatic Solution). Protein complexes have been concerned as essential components in almost every cellular process. X-ray crystallography method is quite useful in studying the nature of protein complexes. In this study, we demonstrated a protein complex completion procedure from a partial molecular replacement (MR) solution using IPCAS. IPCAS is a direct-method aided dual-space iterative phasing and model-building procedure. The test cases were carefully selected from a practical perspective and IPCAS could build the whole complex from one or less than one subunit once molecular replacement method could give a partial solution. Before delivering to IPCAS, MR solution model examination and improvement might be necessary. The IPCAS iteration procedure involves (1) real-space model building and refinement; (2) direct-method aided reciprocal-space phase refinement; and (3) phase improvement through density modification. In our tests, IPCAS is able to extend the full length complex from a less than 30% starting model while conventional model building procedure were unsuccessful.published_or_final_version
Physiology
Doctoral
Doctor of Philosophy
9
Frazier, Richard Andrew. "Macromolecular interactions at polysaccharide surfaces". Thesis, University of Nottingham, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336946.
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10
Hall, P. J. "The macromolecular chemistry of coals". Thesis, University of Newcastle Upon Tyne, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377435.
Testo completo
11
Hsing, Jeff M. (Jeff Mindy) 1972. "Quantification of myocardial macromolecular transport". Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/9068.
Testo completoAbstract (sommario):
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2000.Includes bibliographical references (leaves 66-68).
The needs and impacts of drug administration have evolved from a systemic to a local focus. Local drug delivery would allow a higher local drug concentration at lower systemic toxicity than what can be achieved if delivered systemically. One of the tissues of interest for local delivery is the heart, or myocardium. Increasingly, clinicians are looking to direct myocardial delivery for therapy of complex cardiovascular diseases. Yet, there is little quantitative data on the rates of macromolecular transport inside the myocardium. A porcine model was used in this work as it is most closely similar to humans in size, structure and morphology. Using a technique previously developed in this laboratory to quantify the distribution of macromolecules, the delivery of compounds directly into the myocardium was evaluated. To make quantification generic and not specific for a particular drug or compound, fluorescent-labeled 20kDa and 150kDa dextrans were used to simulate small and large diffusing macromolecules. Diffusion in the myocardium in two directions, transmural and cross-sectional, were investigated to look at diffusion of compounds along and against the myocardium fiber orientation. Fluorescent microscopy was used to quantify concentration profiles, and then the data was fit to a simple diffusion model to calculate diffusivities. This validated the technique developed. The diffusivities of 20kDa dextran in the transmural and cross-sectional direction were calculated to be 9.49 ± 2.71 um2/s and 20.12 ± 4.10 um2/s respectively. The diffusivities for 150kDa were calculated to be 2.39 ± 1.86um 2/s and 3.23 ± 1.76um2/s respectively. The diffusivities of the two macromolecules were statistically different (p < 0.02 for transmural direction and p < 0.01 for cross-section direction). While the diffusion for the larger macromolecule was isotropic, it was not the case for the smaller one. The calculated diffusivity values in the myocardium correlated with previously published data for dextran in the arterial media, suggesting that the transport properties of the myocardium and arterial media may be similar. Applications of quantitative macromolecular transport may include developing novel therapies for cardiovascular diseases in the future.
by Jeff M. Hsing.
S.M.
12
Cicuta, Pietro. "Viscoelasticity of insoluble macromolecular monolayers". Thesis, University of Cambridge, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.619766.
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Tourigny, David Scott. "Overcoming challenges in macromolecular crystallography". Thesis, University of Cambridge, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708430.
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Sterling, William Jerome. "Mechanistic kinetics of macromolecular thermolysis /". For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2002. http://uclibs.org/PID/11984.
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Bloesser, Fabian R. "Chemiluminescent self-reporting macromolecular transformation". Thesis, Queensland University of Technology, 2021. https://eprints.qut.edu.au/211480/1/Fabian%20Raphael_Bloesser_Thesis.pdf.
Testo completoAbstract (sommario):
The present doctoral thesis established advanced optical read-out and characterisation methods for the in-depth analysis of chemical reactions, such as the quantification of reaction events or kinetic analysis, via state-of-the-art chemiluminescence systems. Critically, an optical read-out for the quantification of para-fluoro – thiol reaction events was established employing the chemiluminescence of Schaap’s dioxetane on the one hand, and peroxyoxalate chemiluminescence was employed for the qualitative assessment of single-chain nanoparticle unfolding on the other hand. Both chemiluminescence systems present promising tools for the in-depth characterisation of macromolecular architectures and their transformations.
16
McCaughan, Bridgeen. "Fluorescent sensors associated with macromolecular systems". Thesis, Queen's University Belfast, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.485002.
Testo completoAbstract (sommario):
This thesis begins with an introduction into some of the mechanisms utilised in fluorescent sensing, in particular photoinduced electron transfer and internal charge transfer which \t'\I13re central to the operation of the probes selected for this ,--, l' study. The simplicity and diversity of such sensors is also outlined with examples from the literature showing various compounds designed with specific targets in mind and an indication of future sensors. Chapter two focuses on developing a chemo-sensor to monitor the level of polyhexamethylene biguanide (PHMB), an antimicrobial agent used as an alternative to chlorine in the treatment of swimming pools. Pyrazoline based fluorescent sensors were investigated in order to decrease the magnitude of detection, when compared to the conventional fluorescein derived colorimetric method. Chapter three attempts to add another dimension to the information retrieved from a molecular probe. Sensors were developed to monitor the proton concentration at the boundary of cells. Micelles (CTAC, SLS and Triton-X100) were used as membrane mimics. The sensors were composed of a lipophilic head group connected via a tertiary amine (proton receptor) to the fluorophore (naphthalimide). By varying the lipophilic nature of the head group in a series of compounds, the location of the receptor can be tuned, resulting in a mapping of the local proton density relative to one another. The thesis is concluded with chapters four and five containing the . experimental procedures and references respectively.
17
Shipway, Jennifer Mary. "Coiled coils : electrostatics & macromolecular assemblies". Thesis, University of Sussex, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250122.
Testo completoAbstract (sommario):
The coiled coil is a common and well-studied protein-folding motif. It is based on the seven-residue repeat abcdefg, where a and d residues are largely hydrophobic. Structurally, coiled coils comprise two or more a-helices that are brought together with the a and d residues packing in a well-defined manner to form a hydrophobic core. Interhelical electrostatic interactions are frequently observed between core-flanking g and e residues. There is debate as to whether these interactions are present solely to confer specificity, or whether they also have a role in stabilising the structures. A program, TRAWLER, was written to analyse the core-flanking interactions in a set of high-resolution structural data, and designed proteins were used to investigate the role of these interactions further. It is shown that the electrostatic interactions are stabilising in comparison to a state where the charged residues are present but not interacting. The strength of this stabilisation is strongly context dependent: pairs containing glutamic acid and lysine are more stabilising when the glutamic acid is placed at g and the lysine at e. It is proposed that this is due to the packing of these residues against the surface presented by the core a and d residues. It is noted that previous studies using different a residues in the core exhibit the opposite preference. Further designs include a histidine-based switch and a series of bi-faceted coiled coils. In the latter, coiled-coil repeats were overlaid within a sequence to produce two oligomerisation interfaces. Such sequences are seen in natural a-sheet and a-cylinder structures. Designed peptides were intended to form vertically staggered a-cylinders, leading to the formation of elongated nanotubes. The behaviours of these peptides are presented and the difficulties inherent in such designs are discussed.
18
Wang, Chunhai. "Transport through macromolecular solutions and gels". Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/36422.
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19
Butt, Michael David. "Macromolecular thermodynamics studied by titration calorimetry". Thesis, University of Leicester, 1994. http://hdl.handle.net/2381/34042.
Testo completoAbstract (sommario):
This thesis is centred on the use of an isothermal titration microcalori-meter which can measure heat changes of the order of a few microcalories. The calorimeter provides a rapid and convenient method, incorporating a thermodynamic analysis, for estimating enthalpic pairwise interaction parameters, hjj, for solute-j in aqueous solution. Estimates of hjj for three solutes; urea, monoethylurea and hexamethylenetetramine are reported. Comparisons with published estimates of hjj show good agreement, and confirm the importance of the new technology in calorimetry. The critical micellar concentrations (cmc's) of a series of l-alkyl-4-alkylpyridinium halide and bisquaternary ammonium bromide surfactants are reported, using q, heat change on injection, as the reporter. The standard enthalpy of micelle formation is also obtained, directly, from titration experiments. An equation is derived for the standard Gibbs energy of micelle formation, for these compounds. Thus, the standard entropy is calculated and the driving force (enthalpy or entropy) for micellisation, of these surfactants, is identified. Injection of small aliquots of fusogenic agents (the dianions of dipicolinic acid and sodium sulphate) into aqueous solutions of dioctadecyldimethyl-ammonium bromide (DOAB) vesicles is endothermic at 50 Celsius. For solutions containing greater than equimolar ratios of DOAB and fusogenic agent, the injection process is effectively athermal. The patterns of enthalpy change are attributed to vesicle-dianion interaction (exothermic) and headgroup dehydration (endothermic). Other effects such as the presence of buffer and the interaction of DOAB with halide monoanions are also discussed. Binding of the substrate, chloramphenicol (CM), to the enzyme, chloramphenicol acetyltransferase (CAT), is exothermic. Calorimetric measurements of a series of injections of CM into CAT, and subsequent analysis, yield the binding constant, number of binding sites per macromolecule (enzyme) and the standard enthalpy of binding for the interaction. These three parameters are presented, together with the standard entropy and standard Gibbs energy of binding.
20
De, Munari Sonia. "Biological investigation of glycosylated macromolecular structures". Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:3899afcb-a9c0-4e15-8fd0-c2eff8d5e6b3.
Testo completoAbstract (sommario):
Carbohydrates play a key role in many biological processes. The complex pool of information that these structures are able to express forms the glycocode. Our understanding of this language is limited, due to the complexity of the sugar structures and the diversity of their functions. The work presented in this thesis aims to contribute to our knowledge of their biological significance by building what we will call a Glycomap, a selection of biologically relevant sugars specifically picked to map the in vivo interactions of carbohydrates and explore some of their applications to different macromolecules: proteins, nanoparticles and carbon nanotubes. The controlled glycosylation of proteins still represents a challenge, hence we decided to exploit the ability to diversify carbohydrates from a common precursor, and developed three glycosylating reagents which allowed the use of different glycosylation strategies on different protein structures. In order to follow the in vivo distribution of the selected carbohydrates, we activated them into the 2-imino-2-methoxyethyl derivatives and used them to decorate amino-functionalised magnetic nanoparticles. These nanoparticles were isolated from different tissues after testing in animal models, and their distribution was recorded. As sugars can also be applied to drug delivery systems as targeting agents, we explored the potential of glycosylated carbon nanotubes in the delivery of radionuclides for imaging and radiotherapeutic purposes. Single-walled carbon nanotubes were filled with a radionuclide and after proper functionalisation decorated with different sugars to deliver them to different targets. Finally, we dedicated one last section to the design of functionalised fullerenes as support for the solid-phase synthesis of oligosaccharides. Fullerene derivatives are able to perform homogenous solution phase synthesis with all the advantages of a solid-phase work-up through precipitation. In this thesis we touched several aspects of carbohydrate synthesis, manipulation and applications, to provide new tools which will help elucidate the role of carbohydrates in biological systems.
21
Hatton, Fiona. "Hyerbranched polydendrons : a new macromolecular architecture". Thesis, University of Liverpool, 2014. http://livrepository.liverpool.ac.uk/2006205/.
Testo completoAbstract (sommario):
A novel architecture ‘hyperbranched polydendrons’ (hyp-polydendrons) was produced via the synthesis of low generation dendron initiators for ATRP and subsequent copolymerisation of vinyl and divinyl monomers, to give large polymeric macromolecules containing dendron moieties at the end of each primary chain. Subsequent studies of such materials were performed to assess their ability to form nanoparticles via a nanoprecipitation approach, utilising organic solvent and aqueous nanoparticle formation. It was found that the branched polymers were superior to the linear polymer analogues when assessing their nanoprecipitation behaviour. Mixed initiator hyp-polydendrons were also synthesised by the statistical incorporation of different functionality initiators into the reaction mixture. Here a G2 dendron and different PEG macroinitiators were mixed statistically to produce a series of materials where the primary chain length of the monomer HPMA was also varied. This led to a series of nanoparticles which showed a variation of internal environments when studied using different fluorescent dyes (Nile red and pyrene). Initial pharmacological experiments were promising, however, the initial set of materials did not show prolonged stability in physiologically relevant conditions when using a short PEG macroinitiator (750PEG). Extending the length of the PEG chain (2000PEG initiator) in the mixed polymerisations produced a range of materials with varying solubilities and, therefore, nanoprecipitation behaviour. Nanoparticles were formed which were stable under physiologically relevant conditions and were studied for their cytotoxicity and transcellular permeability in Caco- 2 cells. These materials showed limited toxicity at the concentrations studied and enhanced permeation though the Caco-2 cell monolayer, which is a model of the intestinal epithelial cells. Further studies of the nanoprecipitation behaviour of different molecular weight fractions of the hyp-polydendrons were conducted. This involved separation of molecular weight fractions by dialysis of the hyp-polydendrons against two different good solvents, leading to two HMW fractions and two LMW fractions. Analysis of the nanoprecipitation behaviour of these fractions showed that the HMW fractions produced particles with more narrow PdIs, and the mixing of a low amount of a HMW fraction (1 wt%) with a linear polymer improved the nanoprecipitation behaviour hugely. Encapsulation of two different guest molecules via nanoprecipitation was assessed using FRET, which can report on the proximity of two fluorophores. Dual loading of the particles with DiO and DiI in a 1:1 ratio gave particles which exhibited a FRET signal, therefore indicating that the two fluorophores were located in the same nanoparticle. Somewhat unexpectedly it was found that upon mixing of the two singly loaded particles the observed FRET ratio increased over time until it reached a similar value obtained within the dual loaded nanoparticles. This was possibly due to nanoparticle-nanoparticle collisions. Therefore hyp-polydendrons were produced and utilised to form nanoparticles via a nanoprecipitation approach. Loading of the nanoparticles was achieved and pharmacological benefits were observed for some of the nanoparticle samples, suggesting future benefits for these polymer architectures in nanomedicine applications.
22
Mirzaei, Hanieh. "Manifold optimization methods for macromolecular docking". Thesis, Boston University, 2014. https://hdl.handle.net/2144/11149.
Testo completoAbstract (sommario):
Thesis (Ph.D.)--Boston UniversityThis thesis develops efficient algorithms for local optimization problems encountered in predictive docking of biological macromolecules. Predictive docking, defined as computationally obtaining a model of the bound complex from the coordinates of the two component molecules, is one of the fundamental and challenging problems in computational structural biology. Docking methods generally search for the minima of an energy or scoring function that estimates the binding free energy or, more frequently, the interaction energy, of the two molecules. These energy functions generally have large numbers of local minima, resulting in extremely rugged energy landscapes. Therefore, independently of the algorithm used for sampling the conformational space, virtually all docking algorithms include some type of local continuous minimization of the energy function. Most state-of-the-art algorithms allow for the free movement of all atoms of the two molecules and rely on the minimization of the energy function to enforce structural constraints of the molecules. In contrast this thesis exploits the partial or complete rigidity of the molecules when defining the conformational space. As a result, the local optimization problems are formulated as optimization problems on appropriately defined manifolds. In the case of rigid docking, a novel manifold representation of rigid motions of a body is introduced that resolves many of the optimization difficulties associated with the commonly used manifold for this purposed , the so-called Special Euclidean group, SE(3). These difficulties arise from a coupling that SE(3) introduces between the rotational and translational move of the body. The new representation decouples these moves and results in a more appropriate and flexible optimization algorithm. Experimental results show that the proposed algorithm is an order of magnitude more efficient than the current state-of-the-art algorithms. The proposed manifold optimization approach is then extended to the case of flexible docking. The novel manifold representation of rigid motions is combined with the so-called internal coordinate representation of flexible moves to define a new manifold to which the original manifold optimization algorithm can be directly extended. Computational results show that the resulting optimization algorithm is substantially more efficient than energy minimization using a traditional all-atom optimization algorithm while producing solutions of comparable quality. It is shown that the application of the proposed local optimization algorithm as one of the components of a multi-stage refinement protocol for protein-protein docking contributes significantly to the refinement stage by helping to move the distribution of docking decoys closer to the corresponding bound structures. Finally, it is shown that the approach of the thesis can be substantially generalized to address the problem of minimization of a cost function that depends on the location and poses of one or more rigid bodies, or bodies that consist of rigid parts hinged together. This is a formulation used in a number of engineering applications other than molecular docking.
23
Tosi, Giovanna <1979>. "Macromolecular crystallography: crystallisation and structural determination". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2009. http://amsdottorato.unibo.it/1625/1/TESI_GT.pdf.
Testo completo
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Tosi, Giovanna <1979>. "Macromolecular crystallography: crystallisation and structural determination". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2009. http://amsdottorato.unibo.it/1625/.
Testo completo
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PEDERZOLI, RICCARDO. "MRSAD-PHASING OF LARGE MACROMOLECULAR COMPLEXES". Doctoral thesis, Università degli Studi di Milano, 2020. http://hdl.handle.net/2434/814982.
Testo completoAbstract (sommario):
L’obiettivo del presente lavoro di Tesi è lo studio sistematico del metodo MRSAD, un metodo di fasamento cristallografico che sta diventando sempre più un importante strumento nelle mani dei cristallografi, in particolare per quanto riguarda la risoluzione del crescente numero di strutture biologiche a elevato peso molecolare. Il metodo MRSAD è stato testato su diverse proteine a basso e medio peso molecolare e nel caso del proteasoma 20S umano, sfruttando la presenza di modelli depositati nel Protein Data Bank (PDB) che hanno reso possibile la comparazione e la valutazione dei risultati. L’applicabilità di una procedura generale per il fasamento e la costruzione di un modello nelle fasi MRSAD è stata studiata, cosí come l’effetto di procedure di “density modification”, la completezza dei modelli per Molecular Replacement, la loro accuratezza e la multiplicità dei dati cristallografici. I risultati ottenuti dall’analisi di dati relativi ad un’ampia varietà di sistemi modello permettono di ricavare conclusioni sulle potenzialità e sui limiti del fasamento attraverso MRSAD, e suggeriscono alcune linee guida per la sua applicazione al fine di massimizzare il suo successo. In aggiunta, il fasamento attraverso MRSAD è stato testato positivamente in due casi reali: il primo è rappresentato dall’uso di MRSAD per la risoluzione della struttura del primo recettore del glutammato di pianta. Il secondo riguarda invece l’impiego di MRSAD per il fasamento di antigeni attraverso l’impiego di nano-anticorpi (“nanobodies”) ingegnerizzati con una sequenza in grado di legare ioni di lantanidi, sviluppati recentemente all’interno del gruppo. Il lavoro di Tesi ha anche riguardato la determinazione di alcune strutture rimaste a lungo irrisolte. In questi casi, non è stato possibile ricorrere all’uso di MRSAD a causa della mancanza di dati con segnale anomalo, ed altre strategie di fasamento sono state impiegate. Ognuna delle strutture che è stata risolta rappresenta un caso difficile con le sue proprie peculiarità, ed un ampio spettro di strategie di fasamento e metodi di miglioramento delle fasi è stato impiegato per la loro risoluzione.The objective of the Thesis work is a systematic study of MRSAD-phasing, a crystallographic phasing method that is becoming part of the arsenal available to crystallographers and which represents an important tool for phasing of the increasing number of large macromolecular complexes being crystallized. This method has been tested on small and medium size proteins as well as on more challenging human 20S proteasome data, taking advantage of the existing deposited models which allow for the comparison and evaluation of the results. The applicability of a general procedure for MRSAD-phasing and model building was investigated, as well as the effect of density modification, MR-search model completeness and accuracy and data multiplicity. The results from the tests on a broad variety of systems allow to draw conclusions on the potentialities and limitations of MRSADphasing, suggesting some practical guidelines for its successful application. Moreover, MRSAD-phasing has been tested on two real-life scenarios: the first is represented by the use of MRSAD to solve the structure of the first plant glutamate receptor. The second concerns the use of MRSAD for the phasing of unknown antigens through engineered nanobodies with a lanthanide binding motif recently developed within the group. The Thesis work also dealt with the structure determination of other previously unsolved protein structures, which proved resistant to many attempts at structure solution. In these cases, MRSAD could not be employed because of the unavailability of anomalous signal, and other complex phasing strategies were used. Each structure that was solved represents a difficult case with its own specificities and challenges; in keeping with the Thesis aims, a broad set of phasing strategies and phase improvement methods were used to tackle such structures.
26
Mercadante, Davide. "Macromolecular interaction: pectin, pectin methylesterase and ��-lactoglobulin". Thesis, University of Auckland, 2012. http://hdl.handle.net/2292/19607.
Testo completoAbstract (sommario):
Pectin is a complex polysaccharide found in the plant cell wall. Pathogenic bacteria express a set of enzymes called pectin methylesterase, which start the dismantling of the plant cell wall by de-esterifying homogalacturonan chains in pectin. The efficacy of pectin methylesterase in favouring plant infection may be due to their ability to act processively on pectin chains by catalysing many reactions cycles before dissociating from the polysaccharide. Herein, computational techniques were employed (i) to identify the key interactions between the pectin methylesterase from the bacterium Erwinia chrysanthemi and homogalacturonan oligomers and (ii) to find evidence that it is possible for the enzyme to act processively on pectin carbohydrates. Molecular dynamics simulations demonstrated that the protein binds the polysaccharide chain with different affinity at different sites along the binding interface and that such a strategy is fundamental for the processive catalysis. More importantly, an investigation of the conformational variations of the oligosaccharide lead to a mechanism by which the geometrical restraints impeding the processive action of the enzyme are removed. In a second research project, analytical ultracentrifugation experiments revealed the oligomeric nature of ��-lactoglobulin A and B in solution. The experiments showed that both ��-lactoglobulin variants are mostly dimeric all throughout the pH range investigated (2.5-7.5), although ��-lactoglobulin had been considered mainly monomeric at low pH. Analytical ultracentrifugation experiments quantified, for the first time, the association kinetics of ��-lactoglobulin dimer formation as a function of pH, whereas the dimer stability as a function of ionic strength was investigated by continuum electrostatic calculations. Besides the importance of pectin in plant physiology, complexes between pectin and whey proteins have found a wide use in the food and pharmaceutical industries. However, the basis of the interaction between pectin and whey proteins is still poorly understood. After the identification of ��-lactoglobulin oligomeric state in solution, isothermal titration calorimetry experiments have been employed to investigate the binding between the protein and differently methylated pectin chains. The collected results suggested possible models by which ��-lactoglobulin dimers and pectin interact.
27
Oguzkaya, Funda. "Synthesis Of Macromolecular Catalyst Systems And Applications". Phd thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613565/index.pdf.
Testo completoAbstract (sommario):
SYNTHESIS OF MACROMOLECULAR CATALYST SYSTEMS
AND
APPLICATIONS
Oguzkaya, Funda
PhD., Department of Chemistry
Supervisor: Prof. Dr. Cihangir Tanyeli
September 2011, 144 pages
The thesis mainly proposed to design macromolecular catalyst systems. Such catalysts should follow the way of "Green Chemistry"
with including no metallic ions and have also the ability of reusability. Hence, nitroxide chemistry was chosen as the key point. Catalysts were synthesized with surely including TEMPO as the functional part as the most preferable nitroxide derivative. As a skeleton, norbornene was chosen firstly. Following obtaining 3-(methoxycarbonyl) bicyclo[2.2.1]hept-5-ene-2-carboxylic acid (49), 4-aminoTEMPO was attempted to be inserted in the structure. In this case, 4-aminoTEMPO was preferred as a TEMPO derivative so as to include reactive amine functional group. As a result, two different monomers were obtained. Then, Ring Opening Metathesis Polymerization via first generation Grubbs catalyst was adjusted to reach target macromolecules. Furthermore, as a second type skeleton for the catalyst, Thiophene-Pyrrole-Thiophene (SNS) structure was chosen, since these well-known structures have the ability to polymerize easily. Anelli Oxidation protocol including corresponding catalysts in combination with NaOCl+NaHCO3 (pH 9.1) and KBr resulting in remarkable high activity with low catalyst concentrations typically 1 mol % was chosen for the oxidation of alcohols so as to reach to target aldehydes and ketones. Investigation of other applicable areas via collaborative studies was thought to open the way of electrochromic and biosensor studies as the different points of view. Electropolymerization was performed in a three-electrode cell consisting of an Indium Tin Oxide coated glass slide (ITO) as the working electrode, platinum wire as the counter electrode and Ag wire as the pseudo reference electrode. As the biosensor part, glucose oxidase (GOx) was used as the model enzyme for glucose oxidation in the presence of molecular oxygen. Poly-SNS-based carboxylic acid served as an excellent immobilization matrix for glucose sensing. Key words: TEMPO, Anelli Oxidation
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Schrader, Jeffrey A. "A doppler electrophoresis instrument for macromolecular characterizations". Thesis, This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-05022009-040443/.
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Zhu, Zhixue. "Cyclic oligomers in macromolecular and supramolecular chemistry". Thesis, University of Reading, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272293.
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Farmer, Rohit. "Modelling polyketide synthases and related macromolecular complexes". Thesis, University of Birmingham, 2015. http://etheses.bham.ac.uk//id/eprint/5909/.
Testo completoAbstract (sommario):
Polyketide synthases (PKS) are enzyme complexes that synthesise many natural products of medicinal interest, notably a large number of antibiotics. The present work investigated the mupirocin biosynthesis system, comparing it with similar pathways such as thiomarinol and kalimantacin. The focus was on the structural modelling of the protein complexes involved in antibiotic synthesis, via molecular simulation and the analysis of structural and sequence data. Structural docking of acyl carrier proteins (ACP) cognate for an HMG-CoA synthase orthologue responsible for β-methylation (MupH) identified key residues involved in the recognitions specificity of the interacting partners, further supported by mutagenesis experiments, which thus allows prediction of β-methylation sites in PKS. Moreover, complementation and mutagenesis experiments performed on MupH homologs from kalimantacin and thiomarinol systems suggests specificity between the ACP:HCS proteins in the β-branching suggesting the possibility of engineering multiple specific β-branching modifications into the same pathway. Molecular dynamics simulations of ACPs from the mupirocin cluster revealed that the PKS ACPs form a cavity upon the attachment of the phosphopantetheine and acyl chains similar to what is seen in the fatty acid synthase ACPs and provide a better understanding of the structure function relationship in these small proteins. Molecular docking of the putative cognate substrate with the ketosynthase (KS) homo dimer of module 5 of the MmpA in the mupirocin pathway revealed a loop that may control specificity for the α-hydroxylated substrate and mutagenesis experiments support this proposition.
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Henckel, Julia. "Macromolecular interactions of the tumor suppressor P53". Thesis, University of Cambridge, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621615.
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Saladin, Adrien. "Macromolecular Docking : applications to the RecA nucleofilament". Paris 7, 2009. http://www.theses.fr/2009PA077098.
Testo completoAbstract (sommario):
Les protéines jouent un rôle central dans de nombreux processus cellulaire et peuvent intervenir dans de nombreuses interactions différentes, avec d'autres protéines, de l'ADN, des lipides, ou de petits ligands. La détermination de ces interactions est fondamentale pour pouvoir comprendre des processus biologiques majeurs et de nombreuses méthodes expérimentales ont été développées pour les caractériser. Cependant les méthodes expérimentales sont longues et coûteuses et les méthodes informatisées de prédictions d'interactions pourraient, à terme, fournir dans ce contexte une aide précieuse permettant de guider de futures expériences en biochimie et biologie moléculaire. Le développement logiciels d'amarrage est également un processus difficile mettant en jeu des cycles de conception d'algorithme, d'implémentation et de tests. Au cours de ma thèse, j'ai développé une librairie orientée objet pour favoriser et accélérer les étapes d'implémentation et de tests des méthodes d'amarrage. Cette librairie, programmée en C++ et interfacée avec le langage de script Python, a été utilisée pour mettre au point et tester de nouvelles méthodes appliquées à l'amarrage protéine-ADN et à l'amarrage multi-composants. Des programmes développés à l'aide de cette librairie sont actuellement appliqués à l'étude des modes d'amarrage de l'ADN au complexe RecA, responsable de la recombinaison homologue chez les bactériesProteins play a central role in various cellular processes with various interactions with other proteins, DNA, lipids or small ligands. Because the determination of these interactions is fundamental for understanding key biological processes, several experimental methods have been developed to characterize them. Experimental studies can take a long time and an expensive. Computational methods can therefore be of great help to guide future biochemical experiments. Development of docking software is a long process involving cycles of algorithm conception, programming and tests. During my thesis, I developed an object oriented library to help and speed-up development and tests of docking methods. This library was programmed in C++ with Python bindings, and has been used to test new methods applied to protein-DNA docking and multicomponent docking. Programs made with the help of this library are presently used to study the binding of DNA to the RecA complex, responsible of homologous recombination
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Cashion, Matthew Paul. "Photo-reactive Surfactant and Macromolecular Supramolecular Structures". Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/27714.
Testo completoAbstract (sommario):
For the first time nonwoven fibrous scaffolds were electrospun from a low molar mass gemini ammonium surfactant, N,N–-didodecyl-N,N,N–,N–-tetramethyl-N,N–-ethanediyl-di-ammonium dibromide (12-2-12). Cryogenic transmission electron microscopy (cryo-TEM) and solution rheological experiments revealed micellar morphological transitions of 12-2-12 in water and water:methanol (1:1 vol). Electrospinning efforts of 12-2-12 from water did not produce fibers at any concentration, however, electrospinning 12-2-12 in water:methanol at concentrations greater than 2C* produced, hydrophilic continuous fibers with diameters between 0.9 and 7 μM.
Photo-reactive surfactants were synthesized to electrospin robust surfactant membranes. Before electrospinning it was important to fundamentally understand the structure-property relationship of gemini surfactants. The thermal and solution properties were explored for a series of ammonium gemini surfactants using differential scanning calorimetry (DSC), polarized light microscopy (PLM), and conductivity experiments. The Kraft temperature (Tk) was measured in water and water:methanol (1:1 vol) to investigate the influence of solvent on the surfactant solution properties.
Other experiments investigate how associated photo-curable architectures are applicable in macromolecular architectures, to gain a fundamental understanding of how hydrogen bonding associations influence the photo-reactivity of functionalized acrylic copolymers. Novel hot melt pressure sensitive adhesives (HMPSAs) were developed from acrylic terpolymers of 2-ethylhexyl acrylate (EHA), 2-hydroxyethyl acrylate (HEA), and methyl acrylate (MA) functionalized with hydrogen bonding and photo-reactive functionalities. The synergy of hydrogen bonding and photo-reactivity resulted in higher peel values and rates of cinnamate photo-reactivity with increasing urethane concentration.
Random copolymers of poly(n-butyl acrylate (nBA)-co-2-hydroxyethyl methacrylate (HEMA)) were functionalized with hydrogen bonding and photo-reactive groups to explore the photo-curing of associated macromolecular architectures. The influence of urethane hydrogen bonding on the photo-reactivity of cinnamate-functionalized acrylics was investigated with photo-rheology and UV-vis spectroscopy. Cinnamate-functionalized samples displayed an increase in modulus with exposure time, and the percentage increase in modulus decreased as the urethane content increased. The synergy of hydrogen bonding and photo-reactive groups resulted in higher rates of cinnamate photo-reactivity with increasing urethane concentration.
Electrospun fibers were in situ photo-crosslinked to develop fibrous membranes from cinnamate functionalized low Tg acrylics. Electrospinning was conducted approximately 55 °C above the Tg of the cinnamate acrylate and the electrospun fibers did not retain their fibrous morphology without photo-curing. However, electrospun fibers were collected that retained their fibrous morphology and resisted flow when in situ photo-cured during electrospinning. The intermolecular photo-dimerization of cinnamates resulted in a network formation that prevented the low Tg cinnamate acrylate from flowing.Ph. D.
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Ihms, Elihu Carl. "Integrative Investigation and Modeling of Macromolecular Complexes". The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1429547886.
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Zhang, Borui. "Novel Dynamic Materials Tailored by Macromolecular Engineering". Miami University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=miami1564157701522666.
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Price, Erik Joshua. "EXTREME-ENVIRONMENT PROTECTION USING MACROMOLECULAR COMPOSITE TECHNOLOGY". Case Western Reserve University School of Graduate Studies / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=case1617027732923331.
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Tanaka, Shiho. "Investigation of macromolecular assembly in bacterial microcompartments". Diss., Restricted to subscribing institutions, 2009. http://proquest.umi.com/pqdweb?did=1930321601&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
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Paultre, Danaé Simone Genevieve. "Studies of macromolecular trafficking across Arabidopsis homografts". Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/29518.
Testo completoAbstract (sommario):
Micrografting was used to study the restoration of symplasmic transport at the graft union and to examine the long-distance transport of macromolecules between scion and rootstock. New techniques were established, such as correlative imaging and single-cell analysis in microfluidic devices, to study graft development both in vivo and in vitro. Imaging of Arabidopsis homografts showed that a symplasmic domain develops in the callus stele whose function may be to contain the spread of auxin into the surrounding ground tissue. It was demonstrated, also, that recent reports of organelle transfer at the graft union cannot be explained by the formation of secondary plasmodesmata (PD) at the graft interface. While fused calli did not exchange organelles in vitro, large aggregates of the SIEVE-ELEMENT OCCLUSION RELATED protein fused to YFP (SEOR-YFP; 112 kDa) were unloaded from mature sieve tubes into living cells of the graft partner in vivo, suggesting that vascular remodelling may be a prerequisite for the exchange of organelles at the graft interface. Fusion proteins expressing organelle-targeting signals were found to translocate across the graft junction, unloading into cell files adjacent to the root protophloem. The phloem mobility of a given fusion protein was assessed using bioinformatic and statistical analysis of publicly available data. The size of a protein and its relative abundance in CCs both emerged as defining factors for subsequent phloem transport. The recipient tissue for phloem-unloaded macromolecules was identified as the phloem-pole pericycle (PPP). This cell layer is required to remove macromolecules from the terminus of the protophloem. Induced callose deposition at the PD that connect protophloem SEs to the PPP caused a restriction in unloading and a subsequent arrest in root growth. A non-cell autonomous protein of CC origin, NaKR1-1, is proposed to affect the unloading of macromolecules either by increasing the size exclusion limit (SEL) of PD within the PPP or by enabling a build-up in pressure at the protophloem terminus, due to SUC2 activity, thus allowing phloem unloading.
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Menzel, Jan Philipp. "Wavelength-dependent photoreactivity for macromolecular material design". Thesis, Queensland University of Technology, 2021. https://eprints.qut.edu.au/210196/1/Jan%20Philipp_Menzel_Thesis.pdf.
Testo completoAbstract (sommario):
This thesis is a study of light-induced chemical reactions and the dependence of their reactivity and selectivity on the wavelength of light. Both experimental methods using tunable laser systems and light emitting diodes as well as computational simulation methods are developed that establish an understanding of light-induced bond-forming reactions. Information on wavelength-dependent reactivity is used to predict the rate of LED light induced reactions. The design of systems with chemical reaction pathways that are fully controllable by the wavelength of light paves the way to advanced 3D micro- and nano-printing of macromolecular materials through direct laser writing.
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NITTI, ANDREA. "INNOVATIVE MACROMOLECULAR SYSTEMS FOR ORGANIC PHOTOVOLTAIC APPLICATIONS". Doctoral thesis, Università degli studi di Pavia, 2017. http://hdl.handle.net/11571/1203360.
Testo completoAbstract (sommario):
La Tesi di Dottorato ha sviluppato temi inerenti al design e la realizzazione di polimeri coniugati come componente donor dello strato fotoattivo di celle solari organiche del tipo bulk heterojunction. Sono stati realizzati monomeri innovativi coniugati tramite reazioni di arilazione diretta intramolecolare a partire da coloranti naturali, nuovi sistemi macromolecolari di tipo donor-acceptor incorporanti substrati aromatici fluorurati, e sviluppate nuove metodologie one pot e scalabili per la sintesi di monomeri coniugati da incorporare in sistemi polimerici.
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Cheng, Kimberley. "Single-particle cryo-electron microscopy of macromolecular assemblies". Doctoral thesis, Stockholm : Skolan för teknik och hälsa, Kungliga Tekniska högskolan, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-11769.
Testo completo
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Hospital, Gasch Adam. "High Throughput Computational Studies of Macromolecular Structure Flexibility". Doctoral thesis, Universitat de Barcelona, 2014. http://hdl.handle.net/10803/284440.
Testo completoAbstract (sommario):
Macromolecular structure, and, specifically, its dynamics and flexibility, play a crucial role in its final biological function. Intense efforts are being made to obtain experimental information about macromolecular flexibility. However, despite encouraging advances, we are far from achieving a complete description of the flexibility of a molecular system. Theoretical approaches are convenient alternatives. One of the most used theoretical techniques to account for dynamic information of structures is Molecular Dynamics (MD). Unfortunately, the practical use of MD has been severely limited by its computational cost and by the problems found in the automatic setup of simulations. An alternative to this methods are Coarse-Grained (CG) Dynamics, where, in order to increase computer efficiency, a certain loss of accuracy is accepted, with a significant reduction in structural resolution. Then, using CG algorithms, larger macromolecules and larger timescales can be simulated, reaching the mesoscopic scale.
Nowadays, with the development of new and more efficient simulation engines and the availability of supercomputers and grid platforms (High Performance Computing – HPC), these methods are becoming more and more popular. However, their use in large computational High Throughput (HT) studies requires a complete automation of all the necessary steps in the process of generation of the final trajectory and its subsequent analysis, as well as the building of an efficient storage system, giving the huge amount of data generated by MD/CG methods.
In this thesis, we have designed and implemented a set of bioinformatics tools to port Molecular and Coarse-Grained Dynamics to the HT regime. We have obtained a library of 1,595 protein MD simulations (MoDEL), containing a picture of macromolecular structure flexibility. This large library allowed us to perform HT studies such as the analysis of protein-solvent dynamics, with more than 16 million water molecules available. Finally, all the bioinformatics tools developed in this thesis were included in a set of graphical interfaces as web servers, to ease their use for non-expert users. Addition of pre-configured workflows, integration of macromolecular flexibility analyses and visualization possibilities enhance the value of the final project. The set of web server applications designed and implemented in this thesis is publicly accessible for the scientific community, forming an integrated macromolecular flexibility portal, which can be reached directly http://mmb.irbbarcelona.org/FlexPortal or through the Spanish National Institute of Bioinformatics (INB) portal http://www.inab.org .Las estructuras tridimensionales de las macromoléculas, y en particular, su dinámica y flexibilidad, están íntimamente relacionadas con su función biológica. Debido a la tremenda dificultad del estudio experimental de las propiedades dinámicas de las macromoléculas, se han popularizado un conjunto de técnicas teóricas con las que obtener simulaciones de su movimiento. En los últimos años, los grandes y rápidos avances tanto en la computación como en los estudios teóricos de flexibilidad de macromoléculas han abierto la posibilidad de llevar a cabo estudios masivos de alto rendimiento (High throughput). Sin embargo, para lograr realizar este tipo de estudios, no solo se requieren algoritmos potentes y poder computacional, sino también una automatización de los distintos pasos necesarios en el proceso de cálculo de trayectorias así como de su posterior análisis. Casi tan importante como los cálculos, es necesario un sistema de almacenamiento que permita tanto guardar como consultar de manera eficiente la cantidad enorme de datos generados por el estudio masivo. En esta tesis, se han estudiado, diseñado e implementado diferentes sistemas de automatización high throughput de cálculos de dinámica molecular, tanto atomística como de baja resolución, así como herramientas para su posterior análisis. Así mismo, y para acercar estas metodologías complejas a usuarios no expertos, hemos implementado un conjunto de entornos gráficos a partir de servidores web, que directamente, o vía el portal del Instituto Nacional de Bioinformática (INB), permiten su uso por una amplia comunidad científica.
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Carlmark, Anna. "Complex Macromolecular Architectures by Atom Transfer Radical Polymerization". Doctoral thesis, KTH, Fibre and Polymer Technology, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3740.
Testo completoAbstract (sommario):
Controlled radical polymerization has proven to be a viableroute to obtain polymers with narrow polydispersities (PDI's)and controlled molecular weights under simple reactionconditions. It also offers control over the chain-]ends of thesynthesized polymer. Atom transfer radical polymerization(ATRP) is the most studied and utilized of these techniques. Inthis study ATRP has been utilized as a tool to obtain differentcomplex macromolecular structures.
In order to elaborate a system for which a multitude ofchains can polymerize in a controlled manner and in closeproximity to one another, a multifunctional initiator based onpoly(3-ethyl-3-(hydroxymethyl)oxetane was synthesized. Themacroinitiator was used to initiate ATRP of methyl acrylate(MA). The resulting dendritic-]linear copolymer hybrids hadcontrolled molecular weights and low PDI's. Essentially thesame system was used for the grafting of MA from a solidsubstrate, cellulose. A filter paper was used as cellulosesubstrate and the hydroxyl groups on the cellulose weremodified into bromo-]ester groups, known to initiate ATRP.Subsequent grafting of MA by ATRP on the cellulose made thesurface hydrophobic. The amount of polymer that was attached tothe cellulose could be tailored. In order to control that thesurface polymerization was -eliving-f and hence that thechain-]end functionality was intact, a second layer of ahydrophilic monomer, 2-hydroxyethyl methacrylate, was graftedonto the PMA- grafted cellulose. This dramatically changed thehydrophilicity of the cellulose.
Dendronized polymers of generation one, two and three weresynthesized by ATRP of acrylic macromonomers based on2,2-bis(hydroxymethyl)propionic acid. In the macromonomerroute, macromonomers of each generation were polymerized byATRP. The polymerizations resulted in polymers with low PDI's.The kinetics of the reactions were investigated, and thepolymerizations followed first-order kinetics when ethyl2-bromopropionate was used as the initiator. In the-egraft-]onto-f route dendrons were divergently attached to adendronized polymer of generation one, that had been obtainedby ATRP.
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Gonçalves, Ricardo Henrique. "Síntese coloidal de nanocristais magnéticos com superfície macromolecular". Universidade Federal de São Carlos, 2009. https://repositorio.ufscar.br/handle/ufscar/6547.
Testo completoAbstract (sommario):
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This dissertation describes the development of a synthetic route to obtain colloidal magnetic nanocrystals in solvent of high molar weight and different polarities. Magnetite Nanocrystals ware synthesized by thermal decomposition method using organometallic. With this method was possible to control the size of nanoparticle, obtain high crystallinity and control solubility in several organic solvents. The results showed that the nanocrystals solubility synthesized by this method is governed by polarity of macromolecular solvents. Hydrophobic macromolecule became hydrophobic magnetic nanocrystals. On the other hand, hydrophilic macromolecule result hydrophilic magnetic nanocrystals, like this amphiphilic macromolecule solvent transfer these properties to nanocrystals, turning them into amphiphilic. This solubility behavior was clarified by infrared spectroscopy analysis, indicating the existence of anchored macromolecules on the nanocrystals surface. Besides the crystallographic phase obtained, was also possible obtain superparamagnetic material and high saturation magnetization, revealing so that these colloidal magnetic nanocrystals have potential for biological application.
Esta dissertação descreve o desenvolvimento de uma rota sintética para obter nanocristais magnéticos coloidais em solventes de alta massa molar e diferentes polaridades. Nanocristais de magnetita foram sintetizado por processo de termodecomposição de organometálicos. Utilizando este método foi possível controlar o tamanho de partícula, obter alta cristalinidade e controlar a solubilidade em vários solventes orgânicos. Os resultados mostraram que a solubilidade dos nanocristais sintetizados por este método é governada pela polaridade do solvente macromolecular. Macromoléculas hidrofóbicas tornaram os nanocristais magnéticos hidrofóbicos. Por outro lado, macromoléculas hidrofílicas resultaram em nanocristais magnéticos hidrofílicos. Por fim, solvente macromolecular anfifílico transfere esta propriedade para os nanocristais, tornando-os anfifílicos. Este comportamento de solubilidade foi esclarecido por espectroscopia na região do infravermelho, indicando a presença de macromoléculas ancorada na superfície dos nanocristais. Além da fase cristalográfica de interesse obtida, também foi possível obter um material superparamagnético e com alta magnetização de saturação, revelando desta forma que estes nanocristais magnéticos coloidais possuem potencial para aplicações biológicas.
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Ye, Yun School of Chemical Engineering & Industrial Chemistry UNSW. "Macromolecular fouling during membrane filtration of complex fluids". Awarded by:University of New South Wales. School of Chemical Engineering and Industrial Chemistry, 2005. http://handle.unsw.edu.au/1959.4/33245.
Testo completoAbstract (sommario):
Macromolecular components, including protein and polysaccharides, are viewed as one type of major foulants in the complex feed membrane filtration systems such as membrane bioreactor (MBR). In this thesis, the mechanisms of macromolecular fouling including protein and polysaccharide in the complex feed solution are explored by using Bovine serum albumin (BSA) and alginate as model solution. During the filtration of BSA and washed yeast with 0.22 ????m PVDF membrane, it was found that the critical flux of mixture solution was controlled by washed yeast concentration while the existence of BSA significantly changed the cake reversibility of much larger particles. The fouling mechanisms of alginate, as a model polysaccharide solution, were investigated both in dead end and crossflow membrane filtration. In the dead end experiments, it was found that the cake model appears to fit the entire range of the ultrafiltration data while the consecutive standard pore blocking model and cake model are more applicable to microfiltration membranes. The alginate was featured with high specific cake resistance and low compressibility despite some variations between different membranes. The specific cake resistance ( c ) is similar to c of BSA and actual extracellular polymer substance (EPS) in MBR systems reported in the literature, and higher than that of many colloidal particles. In a system contained alginate-particles mixture, it was found that the existence of alginate dramatically increased the cake specific resistance and decreased the cake compressibility. The fouling mechanism of alginate was also studied using long term cross flow filtration under subcritical flux. A two-stage TMP profile similar to that typically observed in MBR was obtained, confirming the important role of EPS during membrane fouling in MBR. In addition to adsorption, trace deposition of alginate also contributed to the initial slow TMP increase during the subcritical filtration. TMP increase during the long-term filtration was found not only due to the increase of the amount of deposition, but also the increase of specific cake resistance. A combined standard pore blocking and cake filtration model, using a critical pore size for the transition time determination, was developed and fit the experimental results well.
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Barker, Philip. "The introduction of supramolecular architectures into macromolecular arrays". Thesis, University of Warwick, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250967.
Testo completo
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Withe, D. "Some studies of macromolecular initiators of vinyl polmerisation". Thesis, University of Liverpool, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370867.
Testo completo
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Hansell, Claire F. "Tetrazine-norbornene cycloadditions in macromolecular synthesis and functionalisation". Thesis, University of Warwick, 2013. http://wrap.warwick.ac.uk/58244/.
Testo completoAbstract (sommario):
This thesis explores the use of the tetrazine–norbornene inverse electron demand Diels-Alder cycloaddition reaction in polymer and materials science. Chapter 1 gives an introduction to the main concepts and techniques used throughout the thesis. Chapter 2 applies the tetrazine–norbornene reaction to polymer endfunctionalisation and polymer–polymer coupling, in both organic media and water, and establishes the methods (UV/vis and 1H NMR spectroscopies) for monitoring the coupling reaction. Chapter 3 applies the reaction to the modification of a self-assembled polymer micelle and demonstrates its use in tandem with the coppercatalysed azide–alkyne click reaction. The synthesis of an amphiphile bearing both norbornene and alkyne groups is described, the amphiphile is self-assembled and a one-pot dual functionalisation of both the core and shell carried out. Chapter 4 describes the formation and analysis by a variety of methods of sub-20 nm sized polystyrene nanoparticles through the single chain collapse of a norbornene-decorated polymer, ligated with a bisfunctional tetrazine. Chapter 5 discusses attempts to further expand the use of the reaction of tetrazines to polymers bearing pendent alkene groups. The synthesis and characterisation of such polymers is detailed, and attempts to functionalise with a variety of tetrazines described.
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Fogarty, Mark Christopher. "Exercise-induced free radical generation and macromolecular damage". Thesis, Ulster University, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.602700.
Testo completoAbstract (sommario):
This thesis presents experimental research findings into the effects of exercise-induced free oxidative stress. Study 1 - Study one tested the hypothesis that acute high intensity exercise produces free radicals which may cause subsequent damage to DNA, lipids and proteins. It is proposed that the observed DNA damage is the result of the extraction of hydrogen ions from polyunsaturated fatty acids in lipid membranes by a primary free radical species. This reaction initiates the process of lipid peroxidation leading to increased cellular and nuclear membrane permeability exposing DNA to oxidative attack by primary or secondary free radical species. Study 2 - Study two tested the efficacy of chronic watercress supplementation (85g daily for eight weeks) against oxidative stress. Exhaustive exercise demonstrated an increased propensity for oxidative stress (DNA damage and lipid peroxidation) which is potentially mediated by the reactive oxygen species hydrogen peroxide. Chronic supplementation with watercress evoked positive changes in lipid soluble antioxidants which contributed to a reduction in hydrogen peroxide and promoted protection to indices of oxidative stress. Study 3 - The effects of dietary intervention with an acute dose of watercress (85 g 2 hours prior to exercise) on oxidative stress was investigated. Results indicate that watercress acts as potent antioxidant increasing plasma lipid soluble antioxidants. This additional antioxidant protection prevented exercise-induced DNA damage, and decreased lipid peroxidation. Study 4 - The effect of high intensity exercise (100 concentric muscle contractions) and 14 days supplementation with α-lipoic acid on mitochondrial DNA and peripheral indices of oxidative stress were examined. Exercise caused a significant increase in mitochondrial 8-OHdG concentration in both supplemented and non-supplement groups as total antioxidant status decreased. Total antioxidant status of plasma significantly increased in the supplemented group and provided increased antioxidant prophylaxis. Protein oxidation increased with exercise under both supplemented and non-supplemented conditions.
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Gossett, John Jared. "Analysis of macromolecular structure through experiment and computation". Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/51925.
Testo completoAbstract (sommario):
This thesis covers a wide variety of projects within the domain of computational structural biology. Structural biology is concerned with the molecular structure of proteins and nucleic acids, and the relationship between structure and biological function. We used molecular modeling and simulation, a purely computational approach, to study DNA-linked molecular nanowires. We developed a computational tool that allows potential designs to be screened for viability, and then we used molecular dynamics (MD) simulations to test their stability. As an example of using molecular modeling to create experimentally testable hypotheses, we were able to suggest a new design based on pyrrylene vinylene monomers. In another project, we combined experiments and molecular modeling to gain insight into factors that influence the kinetic binding dynamics of fibrin "knob" peptides and complementary "holes." Molecular dynamics simulations provided helpful information about potential peptide structural conformations and intrachain interactions that may influence binding properties. The remaining projects discussed in this thesis all deal with RNA structure. The underlying approach for these studies is a recently developed chemical probing technology called 2'-hydroxyl acylation analyzed by primer extension (SHAPE). One study focuses on ribosomal RNA, specifically the 23S rRNA from T. thermophilus. We used SHAPE experiments to show that Domain III of the T. thermophilus 23S rRNA is an independently folding domain. This first required the development of our own data processing program for generating quantitative and interpretable data from our SHAPE experiments, due to limitations of existing programs and modifications to the experimental protocol. In another study, we used SHAPE chemistry to study the in vitro transcript of the RNA genome of satellite tobacco mosaic virus (STMV). This involved incorporating the SHAPE data into a secondary structure prediction program. The SHAPE-directed secondary structure of the STMV RNA was highly extended and considerably different from that proposed for the RNA in the intact virion. Finally, analyzing SHAPE data requires navigating a complex data processing pipeline. We review some of the various ways of running a SHAPE experiment, and how this affects the approach to data analysis.