Physical Sciences and Mathematics Commons^™

Investigations Into Ambient Ionization Mechanisms: Electrospray Ionization And Direct Analysis In Real Time Mass Spectrometry, Stephen Colin Gibson

Doctoral Dissertations

Mass spectrometry (MS) is an important tool for chemical analyses. Despite the MS requirement for generation of analyte gas-phase ions, many ion source designs afford little-to-no fragmentation, allowing characterization of intact molecules. However, this does not assure that detected ions are representative of the analytes’ natural state. Ionization mechanisms are generally complex and rarely fully understood. Fundamental research into these mechanisms provides greater insight into the relationship between solution chemistry and mass spectra. Work herein addresses aspects of two ambient ionization mechanisms: electrospray ionization (ESI) and Direct Analysis in Real Time (DART).

Ions produced by ESI are dispersed into a …

Biomarker Discovery Of Liver Diseases Using Mass Spectrometry-Based Metabolomics., Xue Shi

Electronic Theses and Dissertations

Metabolomics has emerged as one of the latest of the "-omics" disciplines that can detect metabolite biomarkers in biological samples. The diverse characteristics of metabolites make the analytical platform challenging in metabolomics. Two bioanalytical platforms were developed in this study to investigate metabolite abundance changes under different biological conditions. We first developed a bioanalytical platform that coupled linear trap quadruple - Fourier transform ion cyclotron mass spectrometer (LTQ-FTICR MS) with direct infusion chip-based nano-electrospray ionization (DI-nESI) and applied it to study polychlorinated biphenyls (PCB) effects on non-alcoholic fatty liver disease (NAFLD). We also employed this platform in conjunction with in …

Enzyme, Cosolvent, And Substrate Interactions In Ple Hydrolysis Reactions And Evaluation Of The Stability Of An Unnatural Glutathione Analogue, Maureen Elizabeth Smith

Dissertations

Prochiral diester malonates have been hydrolyzed in the presence of Pig Liver Esterase (PLE). Several of the diesters produced the respective half-ester in moderate to high enantioselectivity. A series of cosolvent assays were performed to evaluate the ability of the cosolvent to influence the enantioselective outcome of the hydrolysis reactions. Ethanol produced the largest changes in enantioselectivity of all solvents evaluated. The isoenzymes of PLE were also evaluated and provided very different enantioselective outcomes than that of crude PLE. A series of NMR titrations was performed to explore the interactions between the substrates and ethanol cosolvents.

Improvements to our previously …

Mass Spectrometry Based Experimental Strategies To Characterize Native And Non-Native Disulfide Bonds In Cysteine-Rich Protein Therapeutics, Adriana Z. Kita

Doctoral Dissertations

The impact post-translational modifications (PTMs) can have on the structure, function, and immunogenicity of protein therapeutics makes it especially important for these protein-based treatments to be well characterized. Mass spectrometry has become instrumental in the examination of enzymatic and non-enzymatic PTMs. Disulfide bonds fall into both of these categories in which native disulfide bonds are formed in the ER by disulfide mediated enzymes and non-native disulfide bonds are often formed by non-enzymatic reducing/oxidizing reactions. Disulfide bonds are particularly important for protein folding and reinforcing higher order structure, and are typically characterized by LC-MS of non-reduced peptides. However, characterizing the disulfide …

Development And Applications Of Mass Spectrometric Methods For Phosphorylation Analysis, Hsin-Pin Ho

Dissertations, Theses, and Capstone Projects

Protein phosphorylation modification regulates numerous cellular functions by a reversible and selective control of kinases and phosphatases. To understand the entire dynamic network of phosphorylation requires sensitive and reliable quantification of phosphorylation, measurements that can be achieved by mass spectrometry. In this research, we established efficient MALDI-mass spectrometric methods as strategies for single- or multi-site phosphorylation quantification without the use of isotopes, chromatography and calibration curves. The methods were assessed by analyzing peptide standards with different single-multiple phosphorylation sites, showing a wide dynamic range, good accuracy and reproducibility. This is the first label-free MALDI method without using a calibration methodology …

Bioinformatic Solutions To Complex Problems In Mass Spectrometry Based Analysis Of Biomolecules, Ryan M. Taylor

Theses and Dissertations

Biological research has benefitted greatly from the advent of omic methods. For many biomolecules, mass spectrometry (MS) methods are most widely employed due to the sensitivity which allows low quantities of sample and the speed which allows analysis of complex samples. Improvements in instrument and sample preparation techniques create opportunities for large scale experimentation. The complexity and volume of data produced by modern MS-omic instrumentation challenges biological interpretation, while the complexity of the instrumentation, sample noise, and complexity of data analysis present difficulties in maintaining and ensuring data quality, validity, and relevance. We present a corpus of tools which improves …

Protein Conformational Studies By Hydrogen/Deuterium Exchange Mass Spectrometry, Antony D. Rodriguez

Electronic Thesis and Dissertation Repository

Proteins are biological macromolecules responsible for the majority of all physiological processes. In order to properly function proteins are required to adopt highly ordered structures. These structural aspects may be found within a single protein or arise from multi-protein complexes. Here hydrogen/deuterium exchange mass spectrometry (HDX-MS) is employed as a tool to determine the extent of protein higher order structure. Exposure to D₂O-based solvent causes the heavier isotope to exchange with amide hydrogens in the polypeptide backbone. This exchange is mainly dependent on protein conformation because the presence of stable hydrogen-bonded secondary structure will impede the incorporation of …

Structural Analysis Of Proteins By Covalent Labeling And Mass Spectrometric Detection, Yuping Zhou

Doctoral Dissertations

Covalent labeling and mass spectrometry are seeing increased use together as a way to obtain insight into the 3-dimensional structure of proteins and protein complexes. Several amino acid specific (e.g., diethylpyrocarbonate) and non-specific (e.g., hydroxyl radicals) labeling reagents are available for this purpose. Diethylpyrocarbonate (DEPC) is a promising labeling reagent because it can potentially probe up to 30% of the residues in the average protein and gives only one reaction product, thereby facilitating mass spectrometric analysis. It was recently reported, though, that DEPC modifications are labile for some amino acids. This dissertation focuses on the improvement of diethylpyrocarbonate (DEPC)-basedcovalent labeling …

Fundamental Studies Of Protein Ionization For Improved Analysis By Electrospray Ionization Mass Spectrometry And Related Methods, Kevin A. Douglass

Dissertations

Mass spectrometry (MS) is an analytical technique in which a sample is converted to gas-phase ions that are subsequently separated and detected. It offers great speed, selectivity, and sensitivity during analysis, characteristics which have enabled it to become a leading method for the study of proteins. The applications of MS for these biologically significant macromolecules range from accurately determining identity and sequence to shedding light on post-translational modifications and protein-molecule interactions. As a first step towards analysis by MS, gas-phase protein ions must be formed. A common method for ionization is electrospray ionization (ESI), where a liquid sample including the …

An Ethnobotanical, Ecological And Lc-Ms-Based Chemometric Investigation Of Phaleria Nisidai, A Traditional Adaptogen Containing Diterpene Esters From Palau, Micronesia, Daniel Kulakowski

Dissertations, Theses, and Capstone Projects

An ethnobotanical, ecological and LC-MS-based chemometric investigation of Phaleria nisidai, a traditional adaptogen containing diterpene esters from Palau, Micronesia

Palau is a country with a rich heritage of traditional medicine still being practiced. One of the most popular and respected remedies in Palau is a tea made from fresh leaves of Phaleria nisidai Kaneh. (Thymelaeaceae). Interviews conducted to determine the use of this plant revealed that it is employed non-specifically to treat a variety of general health concerns. Its use as a prophylactic to keep away sickness, as a 'system cleaner', as well as for strength and energy indicate …

Investigation Into The Cellular Actions Of Carnosine And C-Peptide, Emma H. Gardner

Theses, Dissertations and Capstones

Carnosine is a dipeptide composed of beta-alanine and histidine found exclusively in long-lived animal tissues. The cellular action of carnosine is still under extensive investigation; however, it has been proposed to have a role as an anti-oxidant and oxygen free radical scavenger, a physiological buffer, a heavy metal chelator, and has been implicated as an anti-aging agent.^2,4 Our lab has been studying the interaction between carnosine and heme by analyzing both the effect carnosine has on the glycation of the heme containing protein cytochrome c and the interaction of carnosine with free hemin. We have observed that the addition …

Monitoring Ligand-Induced Nucleic Acid Conformational Changes Using Ion Mobility Spectrometry-Mass Spectrometry, Bill Kenneth Redick

Legacy Theses & Dissertations (2009 - 2024)

Three-dimensional structures of biopolymers frequently dictate the biological role those molecules play. As such, investigation into structure of nucleic acids can provide important information pertaining to how those nucleic acids work. Many nucleic acid species, especially single-stranded RNA, fold into unique structures that allow them to function properly. Metals, and other cationic species, are often bound to the nucleic acid to make folding into the proper structure more favorable by neutralizing the negative charge on the nucleic acid imparted by the phosphate group. This investigation explores tertiary structure of nucleic acids that have been folded in the presence of ligands …

Exploring The Asymmetric Environment Of Various Chiral Catalysts Using A Modified Ion-Trap Mass Spectrometer: Towards The Development Of A Rapid Chiral Catalyst Screening Method, Cary M. Davis

Theses and Dissertations

Since the tragedy of the drug Thalidomide® in the late 1950 to early 1960’s, chirality has been recognized as an important aspect that must be controlled in the drug development process in the pharmaceutical industry. Since then, there has been a considerable movement towards single enantiomer drugs. This demand has presented many challenges for the synthetic organic chemist. Chiral catalysts offer one solution to this problem, as they afford the unique ability to preferentially synthesize one enantiomer. Unfortunately, the design of new chiral catalysts is often empirical, with luck and trial and error necessary due to factors that govern enantioselectivity. …

Methods Development In Biological Mass Spectrometry: Application In Glycoproteomics, Sanja Trajkovic

Theses and Dissertations--Chemistry

Proteomics refers to global characterization of the full set of proteins present in a biological sample. Various analytical disciplines contribute to proteomics but mass spectrometry became method of choice for analysis of complex protein samples.

Mass spectrometry allows for high throughput analysis of the proteome but, moreover, it has the ability to acquire higher-order information such as post-translational modifications (PTM). Glycosylation is the most abundant PTM on eukaryotic proteins.

This dissertation will focus on method development for structural proteomics that will be utilized to explain the glycoproteome of obligate intracellular protozoan parasite Toxoplasma gondii as a model system.

Optimization of …

Particle Formation In Ambient Mass Spectrometry, Thabiso Musapelo

LSU Doctoral Dissertations

A particle sizing system was developed that couples a light scattering particle sizer with a differential mobility analyzer for particle detection and elucidation with the capability for measuring particle sizes in the range of 10 nm to 20 μm. The particle sizing system was used to investigate particle formation that is associated with several methods of atmospheric pressure ion formation used in mass spectrometry: atmospheric pressure matrix-assisted laser desorption ionization (MALDI) and inlet ionization. The methods for particle formation were 1) ultraviolet (UV) laser ablation, 2) infrared (IR) laser ablation, and 3) shock-generated particle formation. Particles formed by UV laser …