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Characterization of UV-crosslinked protein-nucleic acid interfaces by Maldi MS and ESI MS/MSGafken, Philip R. 02 October 2000 (has links)
Graduation date: 2001
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Analysis of electrophilic compounds using an electron monochromator : mass spectrometer systemMazurkiewicz, Paul H. 20 March 1998 (has links)
Graduation date: 1998
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Thermal and mass spectral fragmentation of 2,5-diphenyl-3,4-diazacyclopentadienone-3,4-dioxide /Ward, Carl Edward. January 1972 (has links)
Thesis (M.S.)--Oregon Graduate Center, 1972.
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Investigating the Higher-order Protein Interactions Surrounding the STRIPAK ComplexD'Ambrosio, Lisa 22 July 2010 (has links)
Reversible protein phosphorylation is an essential regulatory mechanism used by eukaryotes to coordinate the biochemical processes of the cell. The PP2A phosphatase functions to dephosphorylate specific proteins originally targeted by stimulus-activated protein kinases. The identification of a sub-network surrounding the human PP2A-Striatin holoenzyme, termed STRIPAK, provides insight into novel mechanisms for PP2A function and regulation. I reveal that STRIPAK participates in at least two mutually-exclusive sub-complexes, one of which contains the putative cortactin-binding protein, CTTNBP2NL. I show that CTTNBP2NL is enriched at the actin cytoskeleton, likely in a STRIPAK-independent manner. This study also reveals that STRIPAK interacts with a subunit of the dynein motor, at least partially, through CTTNBP2NL. This work will serve as a platform for the structural and functional characterization of STRIPAK and will ultimately assist in defining novel mechanisms of regulation and function for the human PP2A phosphatase.
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Investigating the Higher-order Protein Interactions Surrounding the STRIPAK ComplexD'Ambrosio, Lisa 22 July 2010 (has links)
Reversible protein phosphorylation is an essential regulatory mechanism used by eukaryotes to coordinate the biochemical processes of the cell. The PP2A phosphatase functions to dephosphorylate specific proteins originally targeted by stimulus-activated protein kinases. The identification of a sub-network surrounding the human PP2A-Striatin holoenzyme, termed STRIPAK, provides insight into novel mechanisms for PP2A function and regulation. I reveal that STRIPAK participates in at least two mutually-exclusive sub-complexes, one of which contains the putative cortactin-binding protein, CTTNBP2NL. I show that CTTNBP2NL is enriched at the actin cytoskeleton, likely in a STRIPAK-independent manner. This study also reveals that STRIPAK interacts with a subunit of the dynein motor, at least partially, through CTTNBP2NL. This work will serve as a platform for the structural and functional characterization of STRIPAK and will ultimately assist in defining novel mechanisms of regulation and function for the human PP2A phosphatase.
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Developing a TLCspray technique to rapidly characterize small organic chemical in biological fluidTzu-Yang, Su 07 August 2012 (has links)
Analyzing the chemical compounds in biological fluid, such as human blood, by mass spectrometry, sample pretreatments are frequently needed. Those methods, including centrifugation, solid phase extraction (SPE) and liquid-liquid extraction, separate and remove the interferences in biological samples prior to mass analysis. The drawbacks of sample pretreatments mentioned above are time consuming and tedious operation procedures. Thin layer chromatography (TLC) is an analytical tool commonly used for sample purification and separation. To characterize the chemical compounds on TLC plate, coupling TLC with mass spectrometry seems to be a most efficient approach. Since the analytes are buried in the silica layer of TLC plate, it is important to develop a sampling method to transfer analytes from silica layer to mass analyzer. We develop a technique named ¡§TLCspray¡¨ to analyzing the chemical compounds deposited on TLC plate. The concept of TLCspray is similar to the direct electrospray probe (DEP) which has been described by our group: droplets deposed on a metal coated rod can producing ESI plume while applying high voltage. The TLC plate used for TLCspray is cut into stripes with sharp end. Samples are applied on the TLC stripes, than mount onto a holder which fix TLC stripes in front of mass inlet. The mobile phase flow through sample spot, and carry the analyte to the edge of TLC stripe where the fine ESI plume is produced in the effect of electric field. Complex matrixes such as red blood cell (RBC) and proteins are stop on the original position by the silica layer which acts as filter to clean up the unwanted interferences in biological samples. Zolpidem, a drug used to treat insomnia, is chose to demonstrate the sensitivity of TLCspray. The LOQ of zolpidem is 50 ng/mL, and linear dynamic range is 50-1000 ng/mL in human blood. The analysis process of TLCspray for human blood can be finished within 4 minutes. Comparing to other sample pretreatment prior to mass analysis for biological samples, TLCspray can reduce the time needed for clean up the samples without loss the sensitivity.
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Size-selected 2, 5, and 10 nm gold nanoparticles for laser desorption/ionization mass spectrometryStumpo, Katherine Anne 15 May 2009 (has links)
The analytical utility of gold nanoparticles (AuNPs) for laser
desorption/ionization mass spectrometry (LDI-MS) is examined here. An evaluation of
the parameters that affect desorption/ionization show that careful treatments of AuNPs is
needed, as subtle changes in the solution environment can result in subsequent changes
in the mass spectra. A thorough evaluation of the parameters that affect
desorption/ionization of peptides is presented here, and these parameters include: (i)
AuNP-to-analyte ratio, (ii) AuNP size, (iii) solvent, (iv) AuNP surface composition, (v)
pH and buffer effects, (vi) amino acid sequence, and (vii) additives such as fructose or
glycerol. Specifically, controlling the AuNP-to-analyte ratio, pH, peptide composition,
and AuNP size are important parameters for ionization. Additionally, effects of
passivating the AuNP surface with halides or oxyanions was investigated. The presence
of NaF, NaCl, NaBr, and NH4X (X = F, Cl, Br, I) were shown to not significantly affect
analyte ion abundances, whereas addition of NaI strongly suppressed analyte ion yields.
Further physical characterization of the NPs showed that etching had occurred, which
suggests that the surface chemistry of the NPs is important for desorption/ionization. Throughout these investigations, questions remain as to what the internal energies of
peptides are after the desorption/ionization event, and how energy is deposited. Peptide
ion fragmentation is examined under different solution conditions to evaluate the relative
internal energies of peptides, and the fragmentation pattern examined for insight into
fragmentation mechanisms. The data suggest that radical species are important for
fragmentation of peptides when using AuNPs. However, it is likely that multiple
processes are actually directing the fragmentation. Finally, based on the data presented
in this dissertation, a thermal desorption mechanism of pre-formed ions is proposed.
This fundamental research is intended to lay foundations for optimizing the use of
nanoparticles in routine LDI-MS analysis as well as giving insight into nanoparticle
ionization mechanisms. Since very little work has been done in this area, this dissertation
investigates, in detail, many of the subtle characteristics that affect desorption/ionization
of biomolecules when using NPs.
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Structure-property relationships in gas-phase protonated and metalated peptide ionsSlaton, James Garrett 15 May 2009 (has links)
Peptide synthesis and metal doping, combined with mass spectrometric and ion
mobility spectrometric techniques, have provided a picture of the fragmentation behavior
of a large field of homologous peptide ions, represented as XVGVAZG, where the X
amino acid is either arginine, histidine, lysine, aspartic acid or tryptophan and the Z
amino acid is proline, glycine, serine, or histidine. These homologous peptide ions have
been carefully selected to probe the effects of charge site location and secondary
interactions upon the fragmentation chemistry of peptides. Peptides were synthesized on
solid support, doped with appropriate metal salts to attach Li+, Na+, K+, Cu+ and Ag+ ,
and then examined using ion mobility spectrometry, and tandem mass spectrometry,
both high energy collision induced dissociation (CID) and photodissociation using 193-
nm laser light. Molecular dynamics calculations enabled me to derive candidate
structures for these ions that agree with the ion mobility data for the ions.
The fragmentation chemistry and structure selection of the first group of
peptides, those that contain a proline residue, indicate that the presence of high proton
and high metal ion affinity residues at the N-terminal position of the peptide direct the
fragmentation of the highly charge-solvated ions according to a charge site directed mechanism. Further examples of charge-solvated structures and charge-directed
fragmentation are shown for peptides where the sixth amino acid residue has been
replaced with glycine or serine, eliminating the influence of the proline residue in the
sixth position. Photodissociation of the peptides indicates that the position of valine
residues along the peptide backbone influences the types of abundant fragment ions
observed and ai and dai ions are observed exclusively at the site of valine residues. This
observation continued, even when the position of the valine residues were altered by
synthesis, leading me to the conclusion that the fragmentation of these peptides. The
study was expanded to include significantly more complex peptides, those containing
second high proton and high metal ion affinity residues, and though the data are
complex, the influence of charge solvation in those systems is strong as well, according
to my analysis of the candidate structures obtained and the types of fragment ions
observed.
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Application of coincidence ion mass spectrometry for chemical and structural analysis at the sub-micron scaleBalderas, Sara 01 November 2005 (has links)
Surfaces can be probed with a variant of secondary ion mass spectrometry
(SIMS) where the bombardment is with a sequence of single keV projectiles, each
resolved in time and space, coupled with the separate record of the secondary ions (SIs)
ejected from each projectile impact. The goal of this study was to demonstrate an
efficient mode of SIMS where one obtains valid analytical information with a minimum
of projectiles and hence a minimum of sample consumption. An inspection of the
ejected SIs from individual bombardment events will reveal ??super efficient?? collision
cascades i.e., events, where two or more secondary ions were emitted simultaneously. It
has been shown that these coincidental emissions can provide information about the
chemical composition of nano-domains.
Previous studies using coincidence counting mass spectrometry (CCMS)
indicated an enhancement of identifying correlations between SIs which share a common
origin. This variant of SIMS requires an individual projectile impact thus causing SI
emission from a surface area of ~5 nm in radius. Thus, in an event where two or moreSIs are ejected from a single projectile impact, they must originate from atoms and
molecules co-located within the same nano-domain.
Au nanorods covered by a 16-mercaptohexadecanoic acid (MHDA) monolayer
were analyzed using this methodology. A coincidence ion mass spectrum was obtained
for the MHDA monolayer covered Au nanorods which yielded a peak for a Au adduct.
Similar results were obtained for a sample with a MHDA monolayer on a Au coated Si
wafer.
A series of samples consisting of Cu aggregates and AuCu alloys were
investigated by SIMS to demonstrate that this technique is appropriate for characterizing
nanoparticles. The mass spectra of these samples indicated that Au200
4+ is an effective
projectile to investigate the surface of the target because it was able to penetrate through
the poly(vinylpyrrolidone) (PVP) stabilizer that coated the surface of these
nanoparticles. Coincidence mass spectra of the Cu aggregates yielded molecules colocated
within the same nano-domain.
Finally, this methodology was used to investigate surface structural effects on the
occurrence of ??super-efficient?? events. The results indicated that it is possible to
distinguish between two phases of ??-ZrP compounds although the stoichiometry remains
the same.
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Intense-field ionization of atoms and molecules spatially resolved ion detection and ultrashort optical vortices /Strohaber, James. January 1900 (has links)
Thesis (Ph.D.)--University of Nebraska-Lincoln, 2008. / Title from title screen (site viewed Sept. 16, 2008). PDF text: xvi, 196 p. : ill. (some col.) ; 9 Mb. UMI publication number: AAT 3297758. Includes bibliographical references. Also available in microfilm and microfiche formats.
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