A5014296444- Mass Spectrometry Techniques and Applications
- Analytical Chemistry and Chromatography
- Spectroscopy and Quantum Chemical Studies
- Advanced Chemical Physics Studies
- Ion-surface interactions and analysis
- Advanced Proteomics Techniques and Applications
- Metabolomics and Mass Spectrometry Studies
- Microfluidic and Capillary Electrophoresis Applications
- Electrohydrodynamics and Fluid Dynamics
- Electrochemical Analysis and Applications
- Protein Structure and Dynamics
- Analytical chemistry methods development
- Molecular Sensors and Ion Detection
- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Isotope Analysis in Ecology
- Spectroscopy and Laser Applications
- Advanced Chemical Sensor Technologies
- Enzyme Structure and Function
- Atmospheric chemistry and aerosols
- Bacillus and Francisella bacterial research
- Photochemistry and Electron Transfer Studies
- Radioactive element chemistry and processing
- Crystallography and molecular interactions
- Free Radicals and Antioxidants
University of California, Berkeley
2016-2025
University of California System
2014-2025
University of Washington
2025
University of Colorado Boulder
2022-2023
QB3
2009-2022
North Carolina State University
2022
Berkeley College
1994-2021
University of Glasgow
2021
University of Edinburgh
2021
Lawrence Berkeley National Laboratory
2009-2017
Blackbody infrared radiative dissociation (BIRD) spectra of singly and doubly protonated bradykinin its analogues are measured in a Fourier-transform mass spectrometer. Rate constants for as function temperature with reaction delays up to 600 s. From these data, Arrhenius activation parameters the zero-pressure limit obtained. The products ions highly sensitive small changes ion structure. energy (E(a)) pre-exponential (or frequency factor, A) investigated here range from 0.6 1.4 eV 10(5)...
Adeno-associated viruses (AAVs) hold tremendous promise as delivery vectors for gene therapies. AAVs have been successfully engineered—for instance, more efficient and/or cell-specific to numerous tissues—by creating large, diverse starting libraries and selecting desired properties. However, these often contain a high proportion of variants unable assemble or package their genomes, prerequisite any goal. Here, we present showcase machine learning (ML) method designing AAV peptide insertion...
A new method for the dissociation of large ions formed by electrospray ionization is demonstrated. Ions trapped in a Fourier transform mass spectrometer at pressures below 10-8 Torr are dissociated elevating vacuum chamber to temperatures up 215 °C. Rate constants measured and found be independent pressure 10-7 Torr. This indicates that activated absorption blackbody radiation emitted from walls. Dissociation efficiencies as high 100% obtained. There no apparent limit this method; ubiquitin...
The origin of the extent charging and mechanism by which multiply charged ions are formed in electrospray ionization have been hotly debated for over a decade. Many factors can affect number charges on an analyte ion. Here, we investigate poly(propyleneimine) dendrimers (generations 3.0 5.0), cytochrome c, poly(ethylene glycol)s, 1,n-diaminoalkanes from solutions different composition. We demonstrate that absence other factors, surface tension droplet late desolvation process is significant...
The origin of asymmetric charge and mass partitioning observed for gas-phase dissociation multiply charged macromolecular complexes has been hotly debated. These experiments hold the potential to provide detailed information about interactions between macromolecules within complex. Here, this unusual phenomenon is investigated several protein homodimers. Asymmetric in these ions depends on a number factors, including internal energy, state, conformation complex, as well conformational...
A relatively simple model for calculation of the energetics gas-phase proton transfer reactions and maximum charge state multiply protonated ions formed by electrospray ionization is presented. This based on estimates intrinsic reactivity sites protonation point Coulomb interactions. From this model, apparent basicities (GBapp) are calculated. Comparison value to basicity solvent from which an ion enables a be For 13 commonly electrosprayed proteins, our calculated states within average 6%...
The multiple charging of large molecules in electrospray ionization provides key advantages for obtaining accurate molecular weights by mass spectrometry and structural information tandem MSn experiments. Addition glycerol or m-nitrobenzyl alcohol into the solutions dramatically increases both maximum observed charge state abundances high states protein peptide ions. Adding to acidified aqueous cytochrome c shifts most abundant from 17+ 21+, 20+ 23+, average 16.6+ 20.9+. Much less (<1%) is...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElectrostatic Forces and Dielectric Polarizability of Multiply Protonated Gas-Phase Cytochrome c Ions Probed by Ion/Molecule ChemistryPaul D. Schnier, Deborah S. Gross, Evan R. WilliamsCite this: J. Am. Chem. Soc. 1995, 117, 25, 6747–6757Publication Date (Print):June 1, 1995Publication History Published online1 May 2002Published inissue 1 June 1995https://pubs.acs.org/doi/10.1021/ja00130a015https://doi.org/10.1021/ja00130a015research-articleACS...
The multiply charged ions produced by electrospray ionization of peptides molecular masses up to 29 kDa have been successfully introduced into a Fourier transform mass spectrometer unique capabilities for tandem spectrometry, large ion dissociation, and resolution. Electrospray places an unusually high number charges on peptide yielding mass/charge (m/z) values 600-1500; in this range at normal operating pressures (approximately 10(-9) torr; 1 torr = 133.3 Pa) Fourier-transform spectrometry...
We report here infrared spectra of protonated and lithiated valine with varying degrees hydration in the gas phase interpret them help DFT calculations at B3LYP/6-31++G** level. In both species our results clearly indicate that solvation process is driven first by charge site subsequently formation a second shell. The Val·Li+(H2O)4 Val·H+(H2O)4 are strikingly similar region spectrum corresponding to hydrogen-bonded stretches donor water molecules, suggesting cases extended structures formed...
The effects of solvent composition on both the maximum charge states and state distributions analyte ions formed by electrospray ionization were investigated using a quadrupole mass spectrometer. cytochrome c myoglobin, from 47%/50%/3% water/solvent/acetic acid solutions, shift to lower (higher m/z) when 50% fraction is changed water methanol, acetonitrile, isopropanol. This also order increasing gas-phase basicities these solvents, although other physical properties solvents may play role....
The gas-phase structures of protonated and alkali metal cationized arginine (Arg) methyl ester (ArgOMe) are investigated with infrared spectroscopy ab initio calculations. Infrared spectra, measured in the hydrogen-stretch region, provide compelling evidence that changes from its nonzwitterionic to zwitterionic form increasing ion size, transition structure occurring between lithium sodium. For sodiated arginine, for both forms is obtained spectral deconvolution, although predominant....
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTIs Arginine a Zwitterion in the Gas Phase?William D. Price, Rebecca A. Jockusch, and Evan R. WilliamsView Author Information Department of Chemistry, University California Berkeley, 94720 Cite this: J. Am. Chem. Soc. 1997, 119, 49, 11988–11989Publication Date (Web):December 10, 1997Publication History Received14 April 1997Published online10 December inissue 1 1997https://doi.org/10.1021/ja9711627Copyright © 1997 American Chemical...
Molecular activation by blackbody photons, first postulated in 1919 Perrin, plays a dominant role the unimolecular dissociation of large ions trapped at low pressure Fourier-transform mass spectrometer. Under readily achievable experimental conditions, molecular protein ubiquitin equilibrate with radiation field inside vacuum chamber. The internal energy population these is given Boltzmann distribution. From temperature dependence rate constants measured zero-pressure limit, Arrhenius...
The structures of cationized arginine complexes [Arg + M]+, (M = H, Li, Na, K, Rb, Cs, and Ag) protonated methyl ester [ArgOMe H]+ have been investigated in the gas phase using calculations infrared multiple-photon dissociation spectroscopy between 800 1900 cm-1 a Fourier transform ion cyclotron resonance mass spectrometer. structure these depends on identity cation, adopting either zwitterionic form (in salt-bridge complexes) or non-zwitterionic charge-solvated complexes). A diagnostic band...
The structures of isolated alkaline earth metal cationized amino acids are investigated using infrared multiple photon dissociation (IRMPD) spectroscopy and theory. These results indicate that arginine, glutamine, proline, serine, valine all adopt zwitterionic when complexed with divalent barium. IRMPD spectra for these ions exhibit bands assigned to carboxylate stretching modes, spectral signatures acids, lack attributable the carbonyl stretch a carboxylic acid functional group. Structural...
Salts are often necessary to maintain the native structures and functions of many proteins protein complexes, but buffers adversely affect analysis by mass spectrometry (MS). Here, complex ions formed directly from a 150 mM KCl 25 Tris-HCl buffer at pH 7 that is widely used in chemistry mimic intracellular environment. The charge-state distributions not resolved electrospray ionization MS using 1.6 μm diameter emitter tips, resulting no information. In contrast, well-resolved 0.5 which...
The chemical origins of the Hofmeister series are investigated using infrared photodissociation (IRPD) spectroscopy. IRPD spectra SO42−(H2O)n with up to 80 water molecules have a band at ∼3710 cm−1 for n > 43 but not ≤ 43. This corresponds outer-shell "free" OH groups similar those surface bulk water. These results indicate that sulfate dianion has long-range effect on structure, and this is likely be an important factor in its behavior.
Effective temperatures of ions during traveling wave ion mobility spectrometry (TWIMS) analysis were measured using singly protonated leucine enkephalin dimer as a chemical thermometer by monitoring dissociation the into monomer, well subsequent monomer a-, b-, and y-ions, function instrumental parameters. At fixed helium cell TWIMS gas flow rates, extent does not vary significantly with either velocity or height, except at low (<500 m/s) velocities that are commonly used. Increasing rate...
The efficacy of dimethyl sulfoxide (DMSO) as a supercharging reagent for protein ions formed by electrospray ionization from aqueous solution and the mechanism were investigated. Addition small amounts DMSO to solutions containing hen egg white lysozyme or equine myoglobin results in lowering charge, whereas significant increase charge occurs at higher concentrations. Results both near-UV circular dichroism spectroscopy solution-phase hydrogen/deuterium exchange mass spectrometry indicate...
Activation triggers the exchange of subunits in Ca2+/calmodulin-dependent protein kinase II (CaMKII), an oligomeric enzyme that is critical for learning, memory, and cardiac function. The mechanism by which subunit occurs remains elusive. We show human CaMKII holoenzyme exists dodecameric tetradecameric forms, calmodulin (CaM)-binding element can bind to hub destabilize it release dimers. structures from two distantly diverged organisms suggest CaM-binding activated acts as a wedge docking...