Large-Scale Interlaboratory DI-FT-ICR MS Comparability Study Employing Various Systems.

Ultrahigh resolution mass spectrometry (UHR-MS) coupled with direct infusion (DI) electrospray ionization offers a fast solution for accurate untargeted profiling. Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometers have been shown to produce a wealth of insights into complex chemical systems because they enable unambiguous molecular formula assignment even if the vast majority of signals is of unknown identity. Interlaboratory comparisons are required to apply this type of instrumentation in quality control (for food industry or pharmaceuticals), large-scale environmental studies, or clinical diagnostics.

Surface-Induced Dissociation of Protein Complexes in a Hybrid Fourier Transform Ion Cyclotron Resonance Mass Spectrometer.

Mass spectrometry continues to develop as a valuable tool in the analysis of proteins and protein complexes. In protein complex mass spectrometry studies, surface-induced dissociation (SID) has been successfully applied in quadrupole time-of-flight (Q-TOF) instruments. SID provides structural information on noncovalent protein complexes that is complementary to other techniques.

2-Aminoethanol Extraction as a Method for Purifying Sc3N@C80 and for Differentiating Classes of Endohedral Fullerenes on the Basis of Reactivity.

Extraction with 2-aminoethanol is an inexpensive method for removing empty cage fullerenes from the soluble extract from electric-arc-generated fullerene soot that contains endohedral metallofullerenes of the type Sc3N@C2n (n = 34, 39, 40). Our method of separation exploits the fact that C60, C70, and other larger, empty cage fullerenes are more susceptible to nucleophilic attack than endohedral fullerenes and that these adducts can be readily extracted into 2-aminoethanol. This methodology has also been employed to examine the reactivity of the mixture of soluble endohedral fullerenes that result from doping graphite rods used in the Krätschmer-Huffman electric-arc generator with the oxides of Y, Lu, Dy, Tb, and Gd.

Application of desorption electrospray ionization mass spectrometry imaging in breast cancer margin analysis.

Distinguishing tumor from normal glandular breast tissue is an important step in breast-conserving surgery. Because this distinction can be challenging in the operative setting, up to 40% of patients require an additional operation when traditional approaches are used. Here, we present a proof-of-concept study to determine the feasibility of using desorption electrospray ionization mass spectrometry imaging (DESI-MSI) for identifying and differentiating tumor from normal breast tissue.

A rapid MALDI-TOF mass spectrometry workflow for Drosophila melanogaster differential neuropeptidomics.

Background: Neuropeptides are a diverse category of signaling molecules in the nervous system regulating a variety of processes including food intake, social behavior, circadian rhythms, learning, and memory. Both the identification and functional characterization of specific neuropeptides are ongoing fields of research. Matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) analysis of nervous tissues from a variety of organisms allows direct detection and identification of neuropeptides.

Resolving isotopic fine structure to detect and quantify natural abundance- and hydrogen/deuterium exchange-derived isotopomers.

Hydrogen/deuterium exchange (HDX) mass spectrometry (MS) is used for analyzing protein dynamics, protein folding/unfolding, and molecular interactions. Until this study, HDX MS experiments employed mass spectral resolving powers that afforded only one peak per nominal mass in a given peptide's isotope distribution, and HDX MS data analysis methods were developed accordingly. A level of complexity that is inherent to HDX MS remained unaddressed, namely, various combinations of natural abundance heavy isotopes and exchanged deuterium shared the same nominal mass and overlapped at previous resolving powers.

Molecular imaging of drug transit through the blood-brain barrier with MALDI mass spectrometry imaging.

Drug transit through the blood-brain barrier (BBB) is essential for therapeutic responses in malignant glioma. Conventional methods for assessment of BBB penetrance require synthesis of isotopically labeled drug derivatives. Here, we report a new methodology using matrix assisted laser desorption ionization mass spectrometry imaging (MALDI MSI) to visualize drug penetration in brain tissue without molecular labeling.

Sc2(mu2-O) trapped in a fullerene cage: the isolation and structural characterization of Sc2(mu2-O)@C(s)6-C82 and the relevance of the thermal and entropic effects in fullerene isomer selection.

The new endohedral fullerene, Sc(2)(mu(2)-O)@C(s)(6)-C(82), has been isolated from the carbon soot obtained by electric arc generation of fullerenes utilizing graphite rods doped with 90% Sc(2)O(3) and 10% Cu (w/w). Sc(2)(mu(2)-O)@C(s)(6)-C(82) has been characterized by single crystal X-ray diffraction, mass spectrometry, and UV/vis spectroscopy. Computational studies have shown that, among the nine isomers that follow the isolated pentagon rule (IPR) for C(82), cage 6 with C(s) symmetry is the most favorable to encapsulate the cluster at T > 1200 K.

Transformative effects of higher magnetic field in Fourier transform ion cyclotron resonance mass spectrometry.

The relationship of magnetic field strength and Fourier transform ion cyclotron resonance mass spectrometry performance was tested using three instruments with the same design but different fields of 4.7, 7, and 9.4 tesla.

Negative electron transfer dissociation of glycosaminoglycans.

Structural characterization of glycosaminoglycans (GAGs) has been a challenge in the field of mass spectrometry, and the application of electron detachment dissociation (EDD) Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) has shown great promise to GAG oligosaccharide characterization in a single tandem mass spectrometry experiment. In this work, we apply the technique of negative electron transfer dissociation (NETD) to GAGs on a commercial ion trap mass spectrometer. NETD of GAGs, using fluoranthene or xenon as the reagent gas, produces fragmentation very similar to previously observed EDD fragmentation.

Structural characterization of intact proteins is enhanced by prevalent fragmentation pathways rarely observed for peptides.

While collisionally activated dissociation (CAD) pathways for peptides are well characterized, those of intact proteins are not. We systematically assigned CAD product ions of ubiquitin, myoglobin, and bovine serum albumin generated using high-yield, in-source fragmentation. Assignment of >98% of hundreds of product ions implies that the fragmentation pathways described are representative of the major pathways.

Negative electron transfer dissociation of deprotonated phosphopeptide anions: choice of radical cation reagent and competition between electron and proton transfer.

Despite significant developments in mass spectrometry technology in recent years, no routine proteomics sequencing tool is currently available for peptide anions. The use of a molecular open-shell cation is presented here as a possible reaction partner to induce electron transfer dissociation with deprotonated peptide anions. In this negative electron transfer dissociation (NETD) scheme, an electron is abstracted from the peptide anion and transferred to the radical cation.

A seven atom cluster in a carbon cage, the crystallographically determined structure of Sc4(mu3-O)3@Ih-C80.

The tetrahedral array of four scandium atoms with oxygen atoms capping three of the four faces found in Sc(4)(mu(3)-O)(3)@I(h)-C(80) is the largest cluster isolated to date inside a fullerene cage.

Protein conformations can be probed in top-down HDX MS experiments utilizing electron transfer dissociation of protein ions without hydrogen scrambling.

Electron-transfer dissociation (ETD) is evaluated as a technique to provide local information on higher order structure and dynamics of a whole protein molecule. Isotopic labeling of highly flexible segments of a model 18 kDa protein is carried out in solution under mildly denaturing conditions by means of hydrogen/deuterium exchange (HDX), followed by transfer of intact protein ions to the gas phase by means of electrospray ionization, and mass-selection of a precursor ion for subsequent reactions with fluoranthene radical anions. The ETD process gives rise to abundant fragment ions, whose deuterium content can be measured as a function of duration of the HDX reaction in solution.

Sensitive and specific identification of wild type and variant proteins from 8 to 669 kDa using top-down mass spectrometry.

Top-down and bottom-up mass spectrometry methods can generate gas phase fragments and use these to identify proteins. Top-down methods, in addition, can provide the mass of the protein itself and therefore additional structural information. Despite the conceptual advantage of top-down methods, the market share advantage belongs to bottom-up methods as a result of their more robust sample preparation, fragmentation, and data processing methods.

Solvation of electrosprayed ions in the accumulation/collision hexapole of a hybrid Q-FTMS.

In an effort to spectroscopically determine the structures of solvated ions composed of nucleic acid bases and amino acids, methods for their gas-phase synthesis have been studied. Ions were electrosprayed and solvated in the accumulation cell of a hybrid Q-FTICR filled with methanol or water vapor at approximately 10(-2) bar. There were subsequently transferred to the FTICR cell at 10(-10) mbar.

A distorted tetrahedral metal oxide cluster inside an icosahedral carbon cage. Synthesis, isolation, and structural characterization of Sc4(mu3-O)2@Ih-C80.

The remarkably large cluster Sc4(mu3-O)2 has been obtained trapped inside an Ih-C80 cage by conducting the vaporization of graphite rods doped with copper(II) nitrate and scandium(III) oxide in an electric arc under a low pressure helium atmosphere with an added flow of air. The product has been isolated by chromatography and identified by high-resolution mass spectrometry. The structure of Sc4(mu3-O)2@Ih-C80 has been determined by X-ray crystallography on a crystal of Sc4(mu3-O)2@Ih-C80.

Electron transfer dissociation in the hexapole collision cell of a hybrid quadrupole-hexapole Fourier transform ion cyclotron resonance mass spectrometer.

Electron transfer dissociation (ETD) of proteins is demonstrated in a hybrid quadrupole-hexapole Fourier transform ion cyclotron resonance mass spectrometer (Qh-FTICRMS). Analyte ions are selected in the mass analyzing quadrupole, accumulated in the hexapole linear ion trap, reacted with fluoranthene reagent anions, and then analyzed via an FTICR mass analyzer. The hexapole trap allows for a broad fragment ion mass range and a high ion storage capacity.