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Articles 1 - 11 of 11
Full-Text Articles in Physical Sciences and Mathematics
Protein Stability In Solution And In The Gas Phase., Yousef Haidar
Protein Stability In Solution And In The Gas Phase., Yousef Haidar
Electronic Thesis and Dissertation Repository
Electrospray Ionization mass spectrometry (ESI-MS) is widely used for probing proteins, yet many aspects of this technique remain elusive. Using MS, ion mobility spectrometry (IMS), and circular dichroism (CD) spectroscopy, this thesis sheds light on the stability differences of proteins in the gas phase and solution. After a general introduction (Chapter 1), Chapter 2 scrutinizes some aspects of native ESI. Our data highlight the significance of cone voltage in maintaining a native-like fold and show the advantage of using NH4Ac in protein experiments. Chapter 3 focuses on hydrogen/deuterium exchange (HDX)-MS. Several studies have reported that D2O …
Probing The Effects Of Heterogeneous Oxidative Modifications On The Stability Of Cytochrome, Victor Yin, Lars Konermann
Probing The Effects Of Heterogeneous Oxidative Modifications On The Stability Of Cytochrome, Victor Yin, Lars Konermann
Chemistry Publications
Covalent modifications by reactive oxygen species can modulate the function and stability of proteins. Thermal unfolding experiments in solution are a standard tool for probing oxidation-induced stability changes. Complementary to such solution investigations, the stability of electrosprayed protein ions can be assessed in the gas phase by collision-induced unfolding (CIU) and ion-mobility spectrometry. A question that remains to be explored is whether oxidation-induced stability alterations in solution are mirrored by the CIU behavior of gaseous protein ions. Here, we address this question using chloramine-T-oxidized cytochrome c (CT-cyt c) as a model system. CT-cyt c comprises various proteoforms that have …
Interrogating The Quaternary Structure Of Noncanonical Hemoglobin Complexes By Electrospray Mass Spectrometry And Collision-Induced Dissociation., Alexander I M Sever, Victor Yin, Lars Konermann
Interrogating The Quaternary Structure Of Noncanonical Hemoglobin Complexes By Electrospray Mass Spectrometry And Collision-Induced Dissociation., Alexander I M Sever, Victor Yin, Lars Konermann
Chemistry Publications
Various activation methods are available for the fragmentation of gaseous protein complexes produced by electrospray ionization (ESI). Such experiments can potentially yield insights into quaternary structure. Collision-induced dissociation (CID) is the most widely used fragmentation technique. Unfortunately, CID of protein complexes is dominated by the ejection of highly charged monomers, a process that does not yield any structural insights. Using hemoglobin (Hb) as a model system, this work examines under what conditions CID generates structurally informative subcomplexes. Native ESI mainly produced tetrameric Hb ions. In addition, "noncanonical" hexameric and octameric complexes were observed. CID of all these species [(αβ)2 …
Enhancing Protein Electrospray Charge States By Multivalent Metal Ions: Mechanistic Insights From Md Simulations And Mass Spectrometry Experiments., Leanne M Martin, Lars Konermann
Enhancing Protein Electrospray Charge States By Multivalent Metal Ions: Mechanistic Insights From Md Simulations And Mass Spectrometry Experiments., Leanne M Martin, Lars Konermann
Chemistry Publications
The structure and reactivity of electrosprayed protein ions is governed by their net charge. Native proteins in non-denaturing aqueous solutions produce low charge states. More highly charged ions are formed when electrospraying proteins that are unfolded and/or exposed to organic supercharging agents. Numerous studies have explored the electrospray process under these various conditions. One phenomenon that has received surprisingly little attention is the charge enhancement caused by multivalent metal ions such as La3+ when electrospraying proteins out of non-denaturing solutions. Here, we conducted mass spectrometry and ion mobility spectrometry experiments, in combination with molecular dynamics (MD) simulations, to uncover …
Mechanism Of Electrospray Supercharging For Unfolded Proteins: Solvent-Mediated Stabilization Of Protonated Sites During Chain Ejection., Insa Peters, Haidy Metwally, Lars Konermann
Mechanism Of Electrospray Supercharging For Unfolded Proteins: Solvent-Mediated Stabilization Of Protonated Sites During Chain Ejection., Insa Peters, Haidy Metwally, Lars Konermann
Chemistry Publications
Proteins that are unfolded in solution produce higher charge states during electrospray ionization (ESI) than their natively folded counterparts. Protein charge states can be further increased by the addition of supercharging agents (SCAs) such as sulfolane. The mechanism whereby these supercharged [M + zH] z+ ions are formed under unfolded conditions remains unclear. Here we employed a combination of mass spectrometry (MS), ion mobility spectrometry (IMS), and molecular dynamics (MD) simulations for probing the ESI mechanism under denatured supercharging conditions. ESI of acid-unfolded apo-myoglobin (aMb) in the presence of sulfolane produced charge states around 27+, all the way to fully …
Chain Ejection Model For Electrospray Ionization Of Unfolded Proteins: Evidence From Atomistic Simulations And Ion Mobility Spectrometry., Haidy Metwally, Quentin Duez, Lars Konermann
Chain Ejection Model For Electrospray Ionization Of Unfolded Proteins: Evidence From Atomistic Simulations And Ion Mobility Spectrometry., Haidy Metwally, Quentin Duez, Lars Konermann
Chemistry Publications
The ion evaporation model (IEM) and the charged residue model (CRM) represent cornerstones of any discussion related to the mechanism of electrospray ionization (ESI). Molecular dynamics (MD) simulations have confirmed that small ions such as Na+ are ejected from the surface of aqueous ESI droplets (IEM), while folded proteins in native ESI are released by water evaporation to dryness (CRM). ESI of unfolded proteins yields [M + zH] z+ ions that are much more highly charged than their folded counterparts. A chain ejection model (CEM) has been proposed to account for the protein ESI behavior under such non-native conditions …
Conformational Dynamics Of Biomolecules By Trapped Ion Mobility Spectrometry Dynamics, Juan Camilo Molano-Arévalo
Conformational Dynamics Of Biomolecules By Trapped Ion Mobility Spectrometry Dynamics, Juan Camilo Molano-Arévalo
FIU Electronic Theses and Dissertations
One of the main goals in structural biology is to understand the folding mechanisms and three-dimensional structure of biomolecules. Many biomolecular systems adopt multiple structures as a function of their microenvironment, which makes them difficult to be characterized by traditional structural biology tools (e.g., NMR, X-ray crystallography). As an alternative, complementary tools that can capture and sample multiple conformations needed to be developed. In the present work, we pioneered the application of a new variant of ion mobility spectrometry, trapped ion mobility spectrometry (TIMS), which provides high mobility resolving power and the possibility to study kinetically trapped intermediates as a …
Fatty Acid Biomarker Detection For Breast Cancer Using Differential Mobility Spectrometry With Non-Radioactive Ion Source, James Joseph Alberti
Fatty Acid Biomarker Detection For Breast Cancer Using Differential Mobility Spectrometry With Non-Radioactive Ion Source, James Joseph Alberti
USF Tampa Graduate Theses and Dissertations
Differential Mobility Spectrometry (DMS) using a non-radioactive ion source (NRIS) is investigated as a possible medical diagnostic instrument for near real-time detection of breast cancer biomarkers. In previous clinical studies, concentrations of Linoleic, Palmitic and Stearic fatty acids have been observed at different levels in women with carcinoma breast cancer versus women with benign tumors or healthy women showing no signs of breast cancer. Present diagnostic methods require a biopsy of the suspect tissue and a microscopic lab analysis performed to determine its disease state. This process can take hours or days before the patient and doctor are informed of …
Improved Dynamic Headspace Sampling And Detection Using Capillary Microextraction Of Volatiles Coupled To Gas Chromatography Mass Spectrometry, Wen Fan
FIU Electronic Theses and Dissertations
Sampling and preconcentration techniques play a critical role in headspace analysis in analytical chemistry. My dissertation presents a novel sampling design, capillary microextraction of volatiles (CMV), that improves the preconcentration of volatiles and semivolatiles in a headspace with high throughput, near quantitative analysis, high recovery and unambiguous identification of compounds when coupled to mass spectrometry. The CMV devices use sol-gel polydimethylsiloxane (PDMS) coated microglass fibers as the sampling/preconcentration sorbent when these fibers are stacked into open-ended capillary tubes. The design allows for dynamic headspace sampling by connecting the device to a hand-held vacuum pump. The inexpensive device can be fitted …
The Construction And Optimization On An Ion Mobility Spectrometer For The Analysis Of Explosives And Drugs, Hanh Tuyet Lai
The Construction And Optimization On An Ion Mobility Spectrometer For The Analysis Of Explosives And Drugs, Hanh Tuyet Lai
FIU Electronic Theses and Dissertations
Today, over 15,000 Ion Mobility Spectrometry (IMS) analyzers are employed at worldwide security checkpoints to detect explosives and illicit drugs. Current portal IMS instruments and other electronic nose technologies detect explosives and drugs by analyzing samples containing the headspace air and loose particles residing on a surface. Canines can outperform these systems at sampling and detecting the low vapor pressure explosives and drugs, such as RDX, PETN, cocaine, and MDMA, because these biological detectors target the volatile signature compounds available in the headspace rather than the non-volatile parent compounds of explosives and drugs. In this dissertation research volatile signature compounds …
Counter-Flow Ion Mobility Analysis: Design, Instrumentation, And Characterization, Nosa Agbonkonkon
Counter-Flow Ion Mobility Analysis: Design, Instrumentation, And Characterization, Nosa Agbonkonkon
Theses and Dissertations
The quest to achieve high resolution in ion mobility spectrometry (IMS) has continued to challenge scientist and engineers in the field of separation science. The low resolution presently attainable in IMS has continued to negatively impact its utility and acceptance. Until now, efforts to improve the resolution have mainly focused on better instrumentation and detection methods. However, since the resolution of IMS is diffusion limited, it makes sense to address this limitation in order to attain high resolution. This dissertation presents a new IMS technique, which utilizes a high electric field and opposing high gas flow velocity with the aim …