Fong Wai-Yin Karen. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2001 / Includes bibliographical references (p. 173-181). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

by So Mei Po. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (leaves 105-111). / Abstracts in English and Chinese. / Title Page --- p.i / Table of Contents --- p.ii / List of Tables --- p.v / List of Figures --- p.vii / Abbreviations --- p.xi / Acknowledgements --- p.xii / Abstract --- p.xiii / Chapter CHAPTER ONE --- INTRODUCTION / Chapter 1.1 --- Chiral Recognition Detected by Mass Spectrometry --- p.1 / Chapter 1.2 --- Fast Atom Bombardment Mass Spectrometry --- p.7 / Chapter 1.2.1 --- Desorption/Ionization in FAB --- p.7 / Chapter 1.2.1.1 --- Matrix --- p.8 / Chapter 1.2.1.2 --- Atom/Ion Guns --- p.9 / Chapter 1.3 --- Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry --- p.9 / Chapter 1.3.1 --- Development of Matrix-Assisted Laser Desorption/Ionization --- p.10 / Chapter 1.3.2 --- Matrix-Assisted Laser Desorption/Ionization --- p.11 / Chapter 1.3.2.1 --- The Matrix --- p.12 / Chapter 1.3.2.2 --- Mechanisms of Ion Formation --- p.12 / Chapter 1.3.2.2.1 --- Desorption --- p.13 / Chapter 1.3.2.2.2 --- Ionization --- p.13 / Chapter 1.4 --- Blackbody Infrared Radiative Dissociation (BIRD) --- p.14 / Chapter 1.4.1 --- Photodissociation --- p.15 / Chapter 1.4.2 --- Blackbody Infrared Radiative Dissociation --- p.15 / Chapter 1.5 --- Outline of the Present Work --- p.18 / Chapter CHAPTER TWO --- INSTRUMENTATION AND EXPERIMENTAL / Chapter 2.1 --- Time-of-flight Mass Spectrometry --- p.19 / Chapter 2.1.1 --- Delayed Extraction --- p.23 / Chapter 2.1.2 --- Instrumentation --- p.24 / Chapter 2.1.2.1 --- Laser System --- p.24 / Chapter 2.1.2.2 --- Ion Source --- p.26 / Chapter 2.1.2.3 --- Reflector --- p.27 / Chapter 2.1.2.4 --- Detector --- p.27 / Chapter 2.1.2.5 --- Data Acquisition and Computer Control --- p.27 / Chapter 2.2 --- Fourier Transform Ion cyclotron Resonance Mass Spectrometry --- p.28 / Chapter 2.2.1 --- Ion Source --- p.29 / Chapter 2.2.1.1 --- Fast Atom Bombardment Mass spectrometry (FABMS) --- p.29 / Chapter 2.2.2 --- Electrostatic Ion Focusing System --- p.31 / Chapter 2.2.3 --- ICR Analyzer Cell and Magnet --- p.34 / Chapter 2.2.4 --- Data Acquisition and Handling system --- p.38 / Chapter 2.3 --- Experimental --- p.38 / Chapter 2.3.1 --- Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry --- p.38 / Chapter 2.3.1.1 --- Sample Preparation --- p.38 / Chapter 2.3.1.2 --- Mass Spectrometric Analysis --- p.39 / Chapter 2.3.2 --- Fast Atom Bombardment Mass Spectrometry --- p.39 / Chapter 2.3.2.1 --- Sample preparation --- p.39 / Chapter 2.3.2.2 --- Blackbody Infrared Radiative Dissociation --- p.39 / Chapter CHAPTER THREE --- HOST-GUEST COMPLEXES DETECTED BY MATRIX- ASSISTED LASER DESORPTION/IONIZATION MASS SPECTROMETRY / Chapter 3.1 --- Introduction --- p.42 / Chapter 3.2 --- Sample Preparation --- p.45 / Chapter 3.3 --- Results and Discussions --- p.49 / Chapter 3.3.1 --- Cyclodextrins - Cyclic Maltooligosaccharides --- p.49 / Chapter 3.3.2 --- Maltooligosaccharide --- p.55 / Chapter 3.4 --- Conclusions --- p.64 / Chapter CHAPTER FOUR --- DIFFERENTIATION OF ENANTIOMERS USING MALDI-TOF-MS / Chapter 4.1 --- Introduction --- p.65 / Chapter 4.2 --- Experimental --- p.67 / Chapter 4.2.1 --- MALDI-MS Studies --- p.67 / Chapter 4.2.2 --- Calculation --- p.68 / Chapter 4.3 --- Results and Discussions --- p.69 / Chapter 4.3.1 --- MALDI-MS Studies --- p.69 / Chapter 4.3.2 --- Calculations --- p.74 / Chapter 4.4 --- Conclusion --- p.81 / Chapter CHAPTER FIVE --- BLACKBODY INFRARED RADIATION DISSOCIATION (BIRD) OF DIASTEREOCOMPLEXES / Chapter 5.1 --- Introduction --- p.86 / Chapter 5.2 --- Experimental --- p.88 / Chapter 5.3 --- Result and Discussion --- p.89 / Chapter 5.3.1 --- BIRD of Amino-acid/Cyclodextrin complexes --- p.89 / Chapter 5.3.2 --- BIRD of Proton-bound Amino Acid Dimers and Amino Acid/dipeptide Dimers --- p.91 / Chapter 5.4 --- Conclusion --- p.102 / Chapter CHAPTER SIX --- CONCLUSIONS AND FURTHER WORKS / Chapter 6.1 --- Conclusions --- p.103 / Chapter 6.2 --- Further Works --- p.104 / REFERENCES --- p.105

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1979. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Vita. / Includes bibliographical references. / by John Milan Lavoie, Jr. / Ph.D.

Ever since its accidental discovery in the 70s, methylaluminoxane, MAO, has been a popular and widely used activator in olefin polymerization. Hydrolysis of primethylaluminum, Me3Al, produces MAO, an aluminum-, oxygen-, and methyl-containing oligomer. Polyolefins have become one of the most produced polymers, where MAO-activated single-site catalysts are responsible for the synthesis of polymers with highly defined structures. The detailed structure of MAO however, remains a mystery. In order to thoroughly understand the reactivity of MAO, knowing more about it is essential. Electrospray ionization mass spectrometry (ESI-MS) has proven to be a useful technique for studying catalysts and their activation chemistry. It has been shown that MAO is best thought of as a source for the highly reactive and Lewis acidic dimethylaluminum cation, [Me2Al]+. Synthetically, this ion is accessible via the reaction between trityl tetrakis(pentafluorophenyl)borate, [Ph3C]+[B(C6F5)4]- and trimethylaluminum, and this reaction was investigated in detail. A new reaction, substitution of H for CH3 onto the phenyl ring of the trityl carbocation, [Ph3C]+, was detected and found to be general for all trialkylaluminums studied. All instruments with detectors are prone to signal saturation at high concentration and mass spectrometers are no exception. Despite the advantages that ESI-MS offers, saturation can be one of the main obstacles in terms of the accurate quantification of species. This thesis tackles saturation issues in ESI-MS explicitly, because relatively high concentrations were necessary in order to keep unwanted decomposition reactions to a minimum. By detuning various parameters that allows troubleshooting this issue, data that better reflects the reality and the corresponding quantification of species is obtained. With the optimal settings of parameters, quantitative studies and the reactivity regarding the addition of trimethylaluminum, Me3Al, to the trityl carbocation [Ph3C]+ can be better understood. / Graduate

Aptamers have shown a great potential due to their cheaper synthesis and easy chemical modification compared to antibodies, and have been employed in various biological assays and applications throughout the last two decades. Despite of their limitations, such as non-specific binding and low nuclease resistance, aptamers could be successfully used in the biomarker discovery and for the development of the aptamer-based imaging probes for in vitro assays. In this thesis, luminescent aptamer-conjugated nanoparticles were developed and utilized for leukemia cell detection with fluorescent microscopy. It was shown that for the bioconjugation of an aptamer with luminescent nanoparticles it is more beneficial to use carboxyl-modified nanoparticles, which results in a stable luminescence after the conjugation and the absence of unsaturated and unstable conjugates, unlike with amino-modified nanoparticles. Moreover, a cell viability assay was performed and it was revealed that aptamer-conjugated nanoparticles did not induce spontaneous apoptosis and necrosis of leukemia cells, which can be further explored with additional cytotoxicity tests, whether the aptamer-conjugated nanoparticles are biocompatible, or not. Aptamer-based biomarker discovery implies disease biomarker identification, and most commonly used methods are tedious and require a relatively high concentration of captured aptamer-target complexes. For that, AptaBiD was used in order to optimize aptamer-target identification method. Using Sgc8-aptamer, it was first shown with flow cytometry that it binds to both, healthy and malignant T lymphocytes, which requires further improvements for this aptamer to be used for leukemia detection. Among three tested detergents for the aptamer-target purification, DDM happened to be the most suitable one, due to its gentle cell lysis and solubilization properties. However, the cross-linking with formaldehyde has not positively affected the results obtained and could be replaced with photocross-linking in future experiments, which would allow to selectively cross-link an aptamer with a photomodified nucleobase with its target. Lastly, a high number of intracellular proteins identified within samples could be associated with the aptamer non-specific binding and internalization, which could be improved in future with an alternative cell fractionation with a membrane isolation approach used for the identification of transmembrane target protein.

No description available.

Protein function and dysfunction, and their intimate ties to protein structure, has been a core focus of research for several decades. More recently, research into the lack of structure in proteins has reached fever pitch. Intrinsically disordered proteins (IDPs) are proteins (or protein regions) that exist as collapsed or extended, dynamically mobile conformational ensembles, either at secondary or tertiary level, whilst remaining biologically active. The properties of IDPs can impede their study; they are often inherently unstable, are vastly wide-ranging in molecular weight and often difficult to express in large quantities. Mass spectrometry (MS) has evolved into a tool for the study of dynamic systems such as IDPs due to its large dynamic range, high sensitivity, low sample consumption and its lack of bias towards the folded state of a protein. The addition of ion mobility separation to mass spectrometry analysis (IM-MS) provides insight into the conformations adopted by proteins and their complexes, measuring their rotationally averaged collision cross section which can be compared with coordinates from other biophysical techniques such as X-ray crystallography, NMR and to molecular modelling. The work presented in this thesis uses both MS and IM-MS, along with several other biophysical techniques, to interrogate a number of IDPs which are implicated in cancer. Firstly, variable temperature IM-MS is used to probe several proteins of increasing disorder; structured protein cytochrome c, the tumour suppressor protein p53 and the oncoprotein Murine Double Minute 2 (Mdm2), performing IM-MS measurements at a range of temperature from 200 K to 571 K to elucidate the gas-phase unfolding behaviour of each protein. The interaction between p53 and Mdm2 is a current target for cancer drug therapy. Hence MS and IM-MS, alongside circular dichroism and hydrogen-deuterium exchange are next employed to determine the effect of several known small molecule ligands on the conformations adopted by these disordered domains. The significant structuring of both of these disordered proteins upon binding to their respective ligands can be observed using IM-MS, but is not apparent when using other biophysical techniques, highlighting the ability of IM-MS to capture conformational changes occurring in solution on a short timescale. The regulation of disorder in cells is postulated to be mediated by proline residues. I investigate the impact of proline replacement on the populations of conformers presented by p53 using a range of mutants and then go on to study how these mutations impact upon the binding stoichiometry, affinity and conformational preference of p53 for its interaction partner Mdm2. Finally, the disordered melanoma associated antigen 4 MAGE-A4, and its ability to bind to p53 and block its transcriptional activity is probed using MS and IM-MS.

It is well established that lipids play an important role in diseases such as non-alcoholic fatty liver disease and cardiovascular diseases. However, in the past decade, it has come to light that lipids may be important in other diseases; particularly in cancer and neurological disorders. Here, lipid metabolism has been investigated using pre-clinical cancer models for melanoma, glioma, non-small-cell lung cancer and colorectal cancer. The role of lipids in the recovery post-stroke has also been studied. Mass spectrometry imaging offers an ideal tool to study lipids in tissue ex-vivo. Lipids ionise well in a number of mass spectrometry modalities, and hundreds of lipids can be imaged in one mass spectrometry imaging experiment. Furthermore, mass spectrometry imaging offers excellent spatial resolution. In this work, both MALDI-MS and DESI-MS have been used for mass spectrometry imaging. Tumour lipid heterogeneity has been a particular focus of this this project. Heterogeneity exists within tumours, as well as between tumours in the same patient; and this causes major problems for therapy. Owing to the untargeted nature, and high spatial resolution of mass spectrometry imaging, it is an excellent technique to study lipid heterogeneity. Adjacent sections (or in some cases the same section used for mass spectrometry imaging), were used for immunofluorescence and H&E staining. By comparing mass spectrometry images with staining techniques, biological reasons for lipid heterogeneity can be established. Here, a particular focus has been on hypoxia (low oxygen tensions), which is a key contributor to tumour heterogeneity, and is associated with aggressive cancers. Additionally, hypoxia is a feature of ischaemic stroke, and lipids in ischaemic stroke have also been investigated. PET is a non-invasive imaging technique which is able to image a radiolabelled molecule (tracer) in the body. Here, PET has been used as a complementary in-vivo technique to mass spectrometry imaging. The tracers [11C] acetate and [18F]-FTHA have been used to image fatty acid synthase and fatty acid uptake in tumours; both of which are hypothesised to be key in cancer progression. REIMS is a newly established mass spectrometry technique. It is ideal for analysing lipids in cells, as sample preparation is minimal. Here, approaches for cell pellet analysis have been tested, and used to detect lipids in cancer cell lines.

by King Lai Wong. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1997. / Includes bibliographical references (leaves 86-93). / Title Page --- p.i / Table of Contents --- p.ii / List of Tables --- p.iv / List of Figures --- p.v / Abbreviations --- p.viii / Acknowledgements --- p.ix / Abstract --- p.x / Chapter CHAPTER ONE --- INTRODUCTION / Chapter 1.1. --- Mass Spectrometry for Macromolecular Analysis --- p.1 / Chapter 1.2. --- Laser Desorption --- p.3 / Chapter 1.3. --- Development of Matrix-assisted Laser Desorption/Ionization (MALDI) --- p.4 / Chapter 1.4. --- Matrix-assisted Laser Desorption/Ionization --- p.5 / Chapter 1.4.1. --- Laser --- p.6 / Chapter 1.4.2. --- Matrix Selection --- p.6 / Chapter 1.4.3. --- Sample Preparation Methodology --- p.7 / Chapter 1.4.4. --- Ion Formation Process(es) --- p.7 / Chapter 1.4.4.1. --- Desorption --- p.8 / Chapter 1.4.4.2. --- Ionization --- p.9 / Chapter 1.5. --- Time-of-Flight Mass Spectrometry --- p.12 / Chapter 1.6. --- Outline of the Present Work --- p.16 / Chapter CHAPTER TWO --- INSTRUMENTATION AND EXPERIMENTAL / Chapter 2.1. --- Instrumentation --- p.17 / Chapter 2.1.1. --- Laser System --- p.17 / Chapter 2.1.2. --- Ion Source --- p.19 / Chapter 2.1.3. --- Reflector --- p.20 / Chapter 2.1.4. --- Detector --- p.20 / Chapter 2.2. --- Experimental --- p.21 / Chapter 2.2.1. --- Synthesis of nitroanthracene-d9 --- p.21 / Chapter 2.2.2. --- Sample Preparation --- p.22 / Chapter CHAPTER THREE --- STUDIES OF THE EFFECTS OF SOLUTION pH / Chapter 3.1. --- Introduction --- p.25 / Chapter 3.2. --- Sample Preparation --- p.26 / Chapter 3.3. --- Results and Discussion --- p.28 / Chapter 3.3.1. --- Effect of Bronsted Base (NaOH) --- p.28 / Chapter 3.3.2. --- Effect of Lewis Base (Imidazole) --- p.33 / Chapter 3.3.3. --- Effect of Salt Concentration --- p.40 / Chapter 3.4. --- Conclusions --- p.44 / Chapter CHAPTER FOUR --- PROTON SOURCES FOR ION GENERATION IN MALDI-MS / Chapter 4.1. --- Introduction --- p.46 / Chapter 4.2. --- Sample Preparation --- p.47 / Chapter 4.3. --- Results and Discussion --- p.49 / Chapter 4.4. --- Conclusions --- p.55 / Chapter CHAPTER FIVE --- CATIONIZATION PROCESSES IN MALDI-MS : ATTACHMENT OF DIVALENT AND TRIVALENT METAL IONS / Chapter 5.1. --- Introduction --- p.57 / Chapter 5.2. --- Sample Preparation --- p.58 / Chapter 5.3. --- Results and Discussion --- p.60 / Chapter 5.3.1. --- Protonation versus Cationization --- p.60 / Chapter 5.3.2. --- Attachment of Divalent and Trivalent Metal Ions --- p.63 / Chapter 5.4. --- Conclusions --- p.80 / Chapter CHAPTER SIX --- CONCLUDING REMARKS --- p.82 / REFERENCES --- p.86

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Vita. / Includes bibliographical references. / by Agnes Van Langenhove. / Ph.D.