Download or read book Ion Transport by Viscous Gas Flow Through Capillaries and Electrospray Mass Spectrometry of Proteins written by Baiwei Lin and published by . This book was released on 1992 with total page 332 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Electrospray and MALDI Mass Spectrometry written by Richard B. Cole and published by John Wiley & Sons. This book was released on 2011-09-26 with total page 900 pages. Available in PDF, EPUB and Kindle. Book excerpt: Discover how advances in mass spectrometry are fueling new discoveries across a broad range of research areas Electrospray and MALDI Mass Spectrometry brings both veteran practitioners and beginning scientists up to date with the most recent trends and findings in electrospray ionization and matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. In particular, this Second Edition highlights how advances in electrospray and MALDI mass spectrometry are supporting important discoveries in new and emerging fields such as proteomics and metabolomics as well as in traditional areas of chemistry and physics research. Electrospray AND MALDI Mass Spectrometry, SECOND EDITION is divided into five parts: Part A, Fundamentals of ES, explains the fundamental phenomena underlying the electrospray process, including selectivity in ionization and inherent electrochemistry, and concludes with a chapter offering a comparative inventory of source hardware Part B, Fundamentals of MALDI, confronts ionization mechanisms, instrument development, and matrix selection, and includes a final chapter that explores the special application of MALDI to obtain two-dimensional images of spatial distributions of compounds on surfaces Part C, ES and MALDI Coupling to Mass Spectrometry Instrumentation, examines the coupling of these ionization techniques to various mass analyzers, including quadrupole ion trap, time-of-flight, Fourier transform ion cyclotron resonance, and ion mobility mass spectrometers Part D, Practical Aspects of ES and MALDI, investigates analytical issues including quantification, charge-state distributions, noncovalent interactions in solution that are preserved as gas-phase ions, and various means of ion excitation in preparation for tandem mass spectrometry, and offers a guide to the interpretation of even-electron mass spectra Part E, Biological Applications of ES and MALDI, examines the role of mass spectrometry in such areas as peptide and protein characterization, carbohydrate analysis, lipid analysis, and drug discovery Written by a team of leading experts, the book not only provides a critical review of the literature, but also presents key concepts in tutorial fashion to help readers take full advantage of the latest technological breakthroughs and applications. As a result, Electrospray and MALDI Mass Spectrometry will help researchers fully leverage the power of electrospray and MALDI mass spectrometry. The judicious compartmentalization of chapters, and the pedagogic presentation style throughout, render the book highly suitable for use as a text for graduate-level courses in advanced mass spectrometry.

Download or read book Dissertation Abstracts International written by and published by . This book was released on 1993-06 with total page 792 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book American Doctoral Dissertations written by and published by . This book was released on 1992 with total page 796 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Numerical Optimization of Ion Transport in Electrospray Mass Spectrometry written by Kevin S. Rozmiarek and published by . This book was released on 2016 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Capillary Gradient Chromatofocusing mass Spectrometry written by James Anthony Hribar and published by . This book was released on 2011 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt: Gradient chromatofocusing-mass spectrometry is a new technique for protein analysis recently introduced by our research group. Capable of separating and identifying proteins according to pI values and molecular weight, gradient chromatofocusing-mass spectrometry has been achieved by integrating a new ion-exchange chromatography technique called gradient chromatofocusing with a newly discovered buffer system that promotes mass spectrometry detection. Differing from traditional ion-exchange chromatography techniques, gradient chromatofocusing employs specific low molecular weight, volatile buffer components that are introduced onto an ion-exchange HPLC column by programming a binary gradient pumping system to deliver the correct proportions of acidic mobile phase to overcome buffering of the column's stationary phase initially equilibrated with a basic mobile phase thus creating a linear pH gradient through the column. Offering greater control of the slope of the pH gradient and improving separation capabilities through usage of buffers at higher concentrations, gradient chromatofocusing buffer systems offer compatibility with mass spectrometry detection that is not possible using polyampholyte buffers commonly used with traditional ion-exchange chromatography techniques. This compatibility led to the first reporting of ion-exchange chromatography being interfaced with mass spectrometry by a previous group member who used a 2.1 mm i.d DEAE weak anion-exchange column and a 25 mM buffer system consisting of ammonium bicarbonate, pyridine, lactic acid and acetic acid. Furthermore, the focus of this dissertation will be to develop an optimized capillary gradient chromatofocusing-mass spectrometry system (Chapter 4) capable of detecting at the low-levels associated with proteomics by miniaturizing the HPLC system (Chapter 2) and effectively operating with the lowest buffer concentrations possible to generate linear pH gradients to promote compatibility with the mass spectrometer (Chapter 3). Similar to capillary gradient chromatofocusing, other commonly used protein characterization techniques separate proteins according to charge before determining the molecular mass by introducing analytes into a mass spectrometer preferably using capillary chromatography. Advantages and considerations for using capillary columns will be discussed in Chapter 1. In Chapter 2, sensitivity gains and detection limits were compared for various DEAE weak anion-exchange columns with inner diameters ranging from 255 um to 508 um using UV detection. Comparison of sensitivity gains using 255 and 508 um i.d. columns gave results as theoretically expected. Novel to the completion of the work in this study is the packing of PEEK columns in-house using a pressurized column packing technique and development of an on-line pH measurement system for measuring pH gradients prior to analysis of proteins. In Chapter 3, various trials of generating linear pH gradients with various buffer systems are displayed with goals of selecting a buffer system with the lowest concentrations of buffer components possible to promote mass spectrometry compatibility. Linear pH gradients were achieved by reducing concentrations of the initial buffer system composed of ammonium bicarbonate, pyridine, lactic acid and acetic acid from 25 mM to 10 mM by trial and error programming of the gradient system. Efforts were also directed towards including additional buffer components such as collidine to minimize pH drops in unbuffered regions of the gradient resulting from reduced buffering capacity when reducing buffer concentrations. Capable of providing the buffering capacity needed to generate linear pH gradients, the buffer system containing collidine was not used based upon inaccurate pK values determined for proteins, undesirable UV absorbance and shortened lifetime of columns due to incompatibilities with this buffer component. In Chapter 4, the optimized capillary gradient chromatofocusing system using a 255 um i.d. DEAE weak anion-exchange column with a 10 mM ammonium bicarbonate, pyridine, lactic acid and acetic acid buffer system was defined and interfaced with an electrospray ionization triple quadrupole mass spectrometer for detection. Significant improvements are emphasized using the optimized capillary gradient chromatofocusing-mass spectrometry system opposed to the gradient chromatofocusing-mass spectrometry system initially introduced. Detection limits have been reduced significantly and pK values were determined using the optimized capillary GCF-MS system thus showing the utility of this qualitative and quantitative tool in the field of proteomics.

Download or read book Mass Spectrometry Bulletin written by and published by . This book was released on 1994 with total page 648 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Structural and Energetic Studies of Hydrated Gas phase Ions and Biomolecules Using Electrospray Ionization Mass Spectrometry written by Sandra Enid Rodriguez-Cruz and published by . This book was released on 1999 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Investigation of the Fundamentals of Electrospray Ionization and the Separation of Small Molecules Using Ion Mobility Mass Spectrometry written by Kimberly L. Davidson and published by . This book was released on 2017 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ion mobility mass spectrometry (IM-MS) is a gas-phase technique used to separate ions based on their mass-to-charge ratio and collision cross section (i.e. shape). Accurate MS analysis of analytes, such as proteins and protein complexes, relies on the preservation of solution-phase oligomeric distributions during ionization. Gas-phase ions in IM-MS are typically formed using electrospray ionization (ESI), which is a gentle ionization source that preserves noncovalent interactions. One challenge in ESI is that multiple analytes in a single droplet can aggregate during solvent evaporation, biasing the oligomeric states of proteins or protein complexes observed during gas-phase measurements. Initial droplet diameters using electrokinetic nano-ESI were measured and reported to be ~60 nm at an ionization current of 30 nA, which is a typical current for native IM-MS experiments. Nonspecific aggregation of a monomeric protein, myoglobin, was measured as a function of concentration of the protein in solution as well as ionization current (i.e., initial droplet size). Results from those measurements show that nonspecific aggregation increases with ionization current, initial droplet size, and concentration of the analyte in solution. The ionization mechanism of macromolecules from solution to the gas phase was also analyzed by measuring the average charge states of proteins, ranging in mass from 8 – 468 kDa, in four different buffers (ammonium acetate, methylammonium acetate, dimethylammonium acetate, and trimethylammonium acetate). Those results were analyzed according to both the charged residue model and the more recent charged residue-field emission model. In IM, ions are separated using a drift cell that is filled with a neutral gas (typically He or N2) and has an applied electric field. The collision cross sections of 20 common amino acids were measured using a radio-frequency confining drift cell and five different drift gases (He, Ar, N2, CO2 and N2O), which were chosen based on their range of masses and polarizabilities. Drift gas selectivity was quantified using peak capacity and peak-to-peak resolution. Those results show that the identities of the pairs of amino acids separated depends on the drift gas and the number of pairs separated depends on peak capacity. The collision cross sections of ten petroleum-like compounds (containing aromatic isomers and double-bond equivalents) were also measured in He, Ar, N2 and CO2. Those results demonstrate the potential to improve separations of compounds with the same elemental composition by using gases with greater mass and polarizability.

Download or read book Supercharging Methods for Improving Analysis and Detection of Proteins by Electrospray Ionization Mass Spectrometry written by Catherine Cassou Going and published by . This book was released on 2015 with total page 155 pages. Available in PDF, EPUB and Kindle. Book excerpt: The characterization of mechanisms, analytical benefits, and applications of two different methods for producing high charge state protein ions in electrospray ionization (ESI) mass spectrometry (MS), or "supercharging", are presented in this dissertation. High charge state protein ions are desirable in tandem MS due to their higher fragmentation efficiency and thus greater amount of sequence information that can be obtained from them. The first supercharging method, supercharging with reagents (typically non-volatile organic molecules), is shown in this work to be able to produce such highly charged protein ions from denaturing solutions that about one in every three residues carries a charge. The high Coulomb repulsion in these ions results in these ions adopting near-linear gas-phase structures with little to no non-covalent interactions, making them ideal for efficient fragmentation in tandem MS experiments and for the minimization of gas phase HD scrambling during tandem MS. Supercharging with reagents from aqueous solutions typically produces much lower charge states as compared to that observed from a denaturing solution. However, two new reagents are presented in this work that increase protein ion charge past that from denaturing solutions when added to aqueous solutions at just 2% by volume. Increases in charge of up to 168% are reported in the presence of these reagents. The mechanism of the increases in protein ion charging with these reagents from aqueous solutions was investigated with fluorescence experiments and correlated to a destabilization of the protein structure by these reagents toward denaturation. The actual protein denaturation event likely occurs in the ESI droplet itself, consistent with previous studies of the mechanism of supercharging with reagents. Thus, efficient tandem MS of high charge states is possible from ESI of aqueous solutions in which a protein maintains its native or native-like structure and activity, enabling tandem MS analysis of protein modifications, ligand binding, or structural changes in real time. Interestingly, another application for supercharging reagents is protein desalting in the ESI droplet. Supercharging reagents bind to sodium ions, resulting in less non-specific sodium ion adduction to proteins, which can improve signal-to-noise ratios of protein ions, lower limits of detection, and enable the detection of bound ligands or specific binding of salts that might otherwise be obscured by sodium adduction. The second supercharging method, electrothermal supercharging (ETS), requires the presence of particular buffer salts rather than organic reagents to increase protein ion charge in the ESI droplet. An investigation of the effect of several different buffer salts on ETS is presented in this work, revealing that the choice of buffer salt is very important to obtaining effective ETS and that buffer salts likely stabilize or destabilize protein structure in the ESI droplet via Hofmeister effects. The application of ETS to tandem MS of proteins produced by ESI and its utility on proteins ranging in size over an order of magnitude (8.6 kDa to 83.0 kDa) is demonstrated. Hydrogen-deuterium exchange experiments can be performed in aqueous solutions and measured continuously with ETS coupled to tandem MS for protein structure analysis in real time with a spatial resolution of 1.3 residues and without gas phase hydrogen-deuterium scrambling. This work demonstrates the wide applicability of ETS for the study of primary and higher order protein structure for small and large proteins alike.

Download or read book ACS Directory of Graduate Research 1993 written by American Chemical Society. Committee on Professional Training and published by . This book was released on 1993 with total page 1700 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Electrospray Ion Mobility time of Flight Mass Spectrometry for the Detection of Inorganic Anions and Proteins in Aqueous Media written by Steven John Klopsch and published by . This book was released on 2007 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Development of Ion Mobility Mass Spectrometry Instrumentation to Investigate the Gas phase Structures of Protein and Protein Complex Ions written by Samuel J. Allen and published by . This book was released on 2017 with total page 193 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation reports the development of new ion mobility mass spectrometry (IM-MS) instrumentation to analyze protein and protein complex ions. IM-MS is a gas-phase analytical technique that separate ions based on their collision cross section (a description of ion shape) and mass-to-charge ratio. Electrospray ionization of samples from buffered solutions at biologically relevant pH generates “native-like” protein ions, which retain noncovalent interactions and compact conformations. IM-MS analysis enables the determination of the shape and assembly of native-like ions, which can be used to infer information about the solution conformations of biomolecules. New IM devices were developed to improve the informational content obtained from IM-MS experiments. First, an RF-confining drift cell was developed and implemented in a commercial mass spectrometer. Experimental results and ion trajectories implemented using SIMION were used to describe the separation principles of ions in RF-confining drift cells. Those results show that RF-confining drift cells separate ions similarly to traditional IM devices and that applied RF potentials have minimal effects on the effective temperatures of gas-phase ions. The RF-confining drift cells was used to report collision cross sections for 349 ions, 155 of which are for ions that have not been characterized previously using IM. The effects of ionization conditions and analyte solutions on the charge states and collision cross sections of ions was also investigated. An additional IM device based on Structures for Lossless Ion Manipulations (SLIM) was developed. SLIM is an emerging IM technology that can be implemented as modular platforms to perform ion separations, filtering, and trapping. The first collision cross sections determined using SLIM are reported. IM analysis of native-like protein ions shows that those ions exhibit significant structural heterogeneity in the gas-phase. To evaluate the stability and dynamics of native-like protein ions, IM-IM-MS functionality was implemented into the SLIM device. Dynamic gas-phase conformations were observed for native-like protein ions, which has significant implications for the broader community’s interpretation of IM-MS results. The stability of structural subpopulations of native-like ions was investigated as a function of gas-phase ion lifetime at near-ambient temperatures. The conformations of subpopulations evolve continuously in the gas-phase, but even after 4 seconds, the subpopulations exhibit different distributions of collision cross sections. This suggests that native-like ions in IM-MS experiments can retain some memory of their initial gas-phase structures for up to seconds at near-ambient temperature.

Download or read book Fundamental Studies of Protein Ionization for Improved Analysis by Electrospray Ionization Mass Spectrometry and Related Methods written by Kevin A. Douglass and published by . This book was released on 2014 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mass spectrometry 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, where a liquid sample including the protein is charged, nebulized, and evaporated, resulting in bare protein ions. Although ESI has been used in this way for over two decades, many aspects of the protein charging mechanism remain unclear. To address this problem, my research has focused on identifying the factors that determine the extent of protein multiple charging during ESI and improving the ionization of proteins by desorption electrospray ionization. DESI is a method similar to ESI, except that the sample is desorbed from a surface by the spray instead of being present in it from the onset. A simple model was developed that enables the accurate prediction of protein multiple charging observed during ESI-MS if the protein sequence is known. Furthermore, the enhancement of multiple charging that is observed upon the addition of certain organic reagents, a phenomenon known as supercharging, was investigated and a novel mechanism of protein supercharging was proposed. The difficulty in analyzing large proteins by DESI-MS was studied using an innovative approach where DESI was separated into its individual sub-processes and their individual contributions to the DESI process were evaluated. As a result, core limitations to the DESI-MS of large proteins were identified. The results of my cumulative research efforts should lead to the improved MS analysis of proteins by spray ionization methods, including ESI and DESI.

Download or read book Charging of Proteins and Protein Complexes in Native Mass Spectrometry written by Anna Christine Susa and published by . This book was released on 2017 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt: Electrospray ionization (ESI) mass spectrometry is a powerful analytical tool for investigating the identities, structures, functions, and energetics of biomolecules. ESI transfers intact molecules from buffered aqueous solutions in which they are folded or in native conformations into the gas phase for mass spectral analysis. ESI is widely used for the analysis of proteins in mass spectrometry, but the factors that influence charging of protein ions formed by ESI are not well understood. Higher charge states of protein ions are desirable because they fragment more easily in tandem mass spectrometry methods, leading to more sequence coverage than lower charge protein ions. Lower charge protein ions are advantageous in native mass spectrometry when preservation of native protein conformation is desirable. The work described in this dissertation explores factors that control charging of macromolecular ions in native mass spectrometry. This work provides evidence that the charging of macromolecular ions is not significantly limited by ion evaporation of cations, such as alkylammonium or alkali metal ions, or proton transfer to salts that are commonly added to aqueous buffered ESI solutions. In addition, a novel and simple method for ESI of proteins directly from buffers commonly used in biochemistry laboratories is demonstrated. In native mass spectrometry, protein solutions are typically desalted and buffer exchanged into volatile ammonium salt buffers to prevent salt adduction to the protein ions because salt adduction significantly hinders detection and sensitivity of mass spectral analysis. However, some salts are essential for protein structure and function, and this new method of ion desalting allows formation of protein and protein complex ions directly from buffers that contain high ionic strengths of nonvolatile salts to mimic the intracellular and extracellular environments. This technique greatly impacts the way native mass spectrometry is performed because it eliminates the need to reinvestigate properties of the proteins and protein complexes in traditional ammonium salt buffers used in mass spectrometry. Therefore, biochemists will no longer need to adapt their protein solutions to make them suitable for mass spectrometry.

Download or read book Internal Energy Effects on the Solvation and Reactivity of Multiply Charged Biomolecules for Electrospray Ionization Mass Spectroscopy written by and published by . This book was released on 1992 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mild (capillary) interface conditions which do not completely desolvate the ions of proteins in electrospray ionization mass spectrometry (ESI-MS) may be required to probe the higher order structures and weak associations. For the small protein bovine ubiquitin, two ion distributions (unsolvated ions and unresolved solvated ions) were observed. The resolvable solvation for leucine-enkephalin with methanol and water shows that the use of countercurrent N2 flow at the capillary affects the solvation observed. 2 figs. (DLC).

Download or read book Improving Protein Analysis by Desorption Electrospray Ionization DESI MS written by Elahe Honarvar and published by . This book was released on 2019 with total page 155 pages. Available in PDF, EPUB and Kindle. Book excerpt: Electrospray ionization mass spectrometry (ESI-MS) is one of the most well-known and versatile techniques for analyzing a broad range of molecules and it has become one of the leading techniques to study biomolecules, such as proteins. ESI-MS can accurately determine the molecular weight of proteins and provide information about their peptide sequence, post-translational modifications as well as their interaction with other molecules. During ESI-MS analysis, by spraying a sample of proteins, prepared in form of a solution, charged droplets are produced using an electric field. As the solvent molecules gradually evaporate from these droplets, freely hovering bare protein ions remain. The ions are then sampled into the mass spectrometer where they are separated and detected based on their mass to charge (m/z) ratios. In the recent years, a new extension of ESI-MS has been developed that allows analysis of molecules from their immediate surroundings. The technique is called desorption electrospray ionization (DESI-MS). In DESI-MS the sample preparation steps take place in close proximity to ionization step. Such features also provide the advantage of surface analysis and imaging to study spatial distribution of molecules. While DESI shares the ionization mechanism of ESI-MS, it lacks its ability to analyze large biopolymers, and struggles to analyze proteins larger than 25kDa. Previously our research group suggested that the loss in protein signal intensity was not due to problems with physical desorption or ionization, but rather due to incomplete protein dissolution during the desorption step. The studies conducted in this dissertation address this shortcoming by improving protein dissolution during DESI-MS. Effect of addition of volatile ammonium salts during DESI is studied, among which ammonium bicarbonate shows significant improvement in signal to noise (S/N) ratio of proteins, specifically those with higher isoelectric points (pI). The improved S/N ratio seems to be caused by extensive removal of potassium from the protein ions. While these additives lead to improvements in the performance of DESI, their addition does not cause the same effect in ESI. The different effects of these additives in DESI and ESI are studied in terms of proteins signal intensity, S/N ratio as well as charge state distribution. The effect of addition of the amino acid of serine to the electrospray solvent of DESI is investigated. For proteins with different molecular weights and pI values, serine shows promising improvements in the signal intensity. Application of vaporized organic reagents in the nebulizing gas flow of the electrospray solvent of DESI is described. To add these vapors, DESI sprayer is enclosed and the vapor is delivered to the inner environment of the enclosure. By adding the vapor of ethyl acetate during DESI analysis of proteins, the attained signal intensity is increased. Such improvements can potentially be combined during a single analysis to further better the outcome of protein analysis by DESI-MS.