Abstract: Reagents and methods for extracting and stabilizing metabolites at room temperature and methods in which metabolites and one or more of proteins, lipids and nucleic acids are extracted from a single sample in a unified workflow.

Abstract: Reagents and methods for extracting and stabilizing metabolites at room temperature and methods in which metabolites and one or more of proteins, lipids and nucleic acids are extracted from a single sample in a unified workflow.

Abstract: Provided herein is a method comprising one or more of the following steps: (a) lysing cells of a biological sample and contacting the biological sample with an amount of ionic liquid sufficient to denature intracellular metabolic enzymes in the biological sample to produce a contacted cellular sample; (b) mixing the contacted cellular sample with an organic solvent to produce an ionic liquid-organic solvent composition; (c) mixing the contacted cellular sample with the organic solvent to produce a dispersed microdroplet ionic liquid-organic solvent composition; (d) contacting the ionic liquid-organic solvent composition with an ion exchange composition to produce a second ionic liquid-organic solvent composition; (d) separating the ionic liquid from the organic solvent; and (e) extracting metabolites from the ionic liquid. Kits and systems for practicing the subject methods are also provided.

Abstract: A method for removing an ionic liquid from an aqueous sample is provided. In some embodiments, the method includes: (a) combining an aqueous sample including an ionic liquid with an ion exchanger composition including an ion exchanger counterion to produce a solution including a fluorous salt of the ionic liquid, where at least one of the ionic liquid and the ion exchanger counterion is fluorinated; (b) contacting the solution with a fluorous affinity material, thereby removing fluorous salt from the solution and producing an aqueous eluate; and (c) collecting the aqueous eluate. In certain embodiments, the method further includes: contacting a cell with an ionic liquid composition to lyse the cell and produce an aqueous sample; and contacting the aqueous sample with a reverse phase substrate, thereby adsorbing proteins and/or lipids of the cell on the substrate. Compositions, kits and systems for practicing the subject methods are also provided.

Abstract: A sample droplet generator transforms a segmented array of sample material into a continuous stream of droplets containing analytes. The droplets may serve as a sample source for a wide range of detectors and analytical instruments. As one example, the droplets may be introduced into an ion source of a spectrometer that measures ions produced from the droplets or photons emitted from the droplets.

Abstract: A sample droplet generator transforms a segmented array of sample material into a continuous stream of droplets containing analytes. The droplets may serve as a sample source for a wide range of detectors and analytical instruments. As one example, the droplets may be introduced into an ion source of a spectrometer that measures ions produced from the droplets or photons emitted from the droplets.

Abstract: A method for removing an ionic liquid from an aqueous sample is provided. In some embodiments, the method includes: (a) combining an aqueous sample including an ionic liquid with an ion exchanger composition including an ion exchanger counterion to produce a solution including a fluorous salt of the ionic liquid, where at least one of the ionic liquid and the ion exchanger counterion is fluorinated; (b) contacting the solution with a fluorous affinity material, thereby removing fluorous salt from the solution and producing an aqueous eluate; and (c) collecting the aqueous eluate. In certain embodiments, the method further includes: contacting a cell with an ionic liquid composition to lyse the cell and produce an aqueous sample; and contacting the aqueous sample with a reverse phase substrate, thereby adsorbing proteins and/or lipids of the cell on the substrate. Compositions, kits and systems for practicing the subject methods are also provided.

Abstract: Provided herein is a method comprising one or more of the following steps: (a) lysing cells of a biological sample and contacting the biological sample with an amount of ionic liquid sufficient to denature intracellular metabolic enzymes in the biological sample to produce a contacted cellular sample; (b) mixing the contacted cellular sample with an organic solvent to produce an ionic liquid-organic solvent composition; (c) mixing the contacted cellular sample with the organic solvent to produce a dispersed microdroplet ionic liquid-organic solvent composition; (d) contacting the ionic liquid-organic solvent composition with an ion exchange composition to produce a second ionic liquid-organic solvent composition; (d) separating the ionic liquid from the organic solvent; and (e) extracting metabolites from the ionic liquid. Kits and systems for practicing the subject methods are also provided.

Abstract: Crosslinking reagents and methods for using the same for analysis of protein-protein interactions, are provided. The crosslinking reagents include a trifunctional scaffold that links two protein linking groups to each other and branches to link an affinity tag, where the protein linking groups can be fragmented from the scaffold. The distance between the two protein linking groups can be selected to crosslink two proteins of a protein complex via accessible amino acid residues. Also provided are crosslinked polypeptide compounds and kits that include crosslinking reagents. These reagents and methods find use in a variety of applications in which crosslinking of proteins in desired.

Abstract: Crosslinking reagents and methods for using the same for analysis of protein-protein interactions, are provided. The crosslinking reagents include a trifunctional scaffold that links two protein linking groups to each other and branches to link an affinity tag, where the protein linking groups can be fragmented from the scaffold. The distance between the two protein linking groups can be selected to crosslink two proteins of a protein complex via accessible amino acid residues. Also provided are crosslinked polypeptide compounds and kits that include crosslinking reagents. These reagents and methods find use in a variety of applications in which crosslinking of proteins in desired.

Abstract: Compounds, compositions, methods for sequencing proteins and peptides, and methods for identifying proteins and peptides in a mixture, are disclosed. Compounds of formula A-B-C wherein A is a nucleophilic reactive group, B is a detectable moiety capable of being isotopically labeled, and C is a charge replacement group, are used to label the peptides at the N-terminus or the C-terminus. The tagged peptides can then be analyzed by mass spectroscopy.

Abstract: A method for rapid detection and possibly identification of protein complexes is disclosed. The method utilizes a two stage high resolution chromatographic analysis and a reversible crosslinker to detect and identify protein complexes. The identification of protein complexes may be further improved by mass spectrometry analysis of chromatographic fractions containing the complexes. A system for implementing the method is also provided.

Abstract: A method for the characterization of protein-protein interactions based on diagonal mass spectrometry is provided. Proteomic samples containing interacting proteins are chemically crosslinked either in vivo or in vitro. After a high resolution chromatographic separation, crosslinked interacting proteins are introduced directly into a mass spectrometer. During the data acquisition, the mass spectrometer alternates between two discrete acquisition states. In the first acquisition state, the crosslinked complexes are analyzed. In the second acquisition state, the crosslinking is cleaved and the mass spectra of the dissociated proteins are collected. Following the data acquisition, the raw mass spectral data is deconvoluted and reconstructed into a diagonal MS plot of crosslinked proteins vs. component proteins to explore protein-protein interactions.

Abstract: The present invention provides methods for analyzing a peptide or peptides of interest in a protein sample using a combination of a relatively generic isotope tag with a decoupled selection process, allowing simplified customization of the application with a single reagent. These methods comprise providing a first and a second protein sample; labeling the first protein sample with a first Universal Peptide Isotope Tag (U-PIT) reagent and the second protein sample with a second U-PIT reagent; separating the peptide of interest from the combined first and second protein samples; and determining the relative amount of the first U-PIT reagent and the second U-PIT reagent bound to the peptide or peptides of interest. The U-PIT label of the present inventive methods has the following general formula A-B-C wherein A is a nucleophilic reactive group, B is a detectable moiety that can be isotopically labeled, and C is a charge replacement group.

Abstract: Methods and kits are disclosed for detecting one or more proteins in a sample suspected of containing a plurality of the proteins. An assay medium comprising the sample and a capture agent for each of the proteins is incubated. Each of the capture agents comprises a protein-binding portion and a nucleic acid portion. Incubation is carried out under conditions for binding of the capture agents to the proteins to form capture agent-protein complexes. A mixture comprising the complexes is separated from the capture agents. The nucleic acid portions of the complexes in the mixture are then related to the presence or amount of one or more of the proteins in the sample.

Abstract: Methods, devices and kits are disclosed for detecting one or more target proteins in a sample suspected of containing a plurality of the target proteins. An assay medium comprising the sample is incubated with a surface of a substrate comprising a plurality of capture agents bound to the surface in a predetermined arrangement or pattern. For each target protein, at least two capture agents specific for different binding sites on the target protein are employed. The two capture agents are disposed on the surface of the substrate in a spatial relationship so that both bind to a molecule of the target protein, preferably the same molecule of the target protein. The binding to the molecule of the target protein is usually substantially simultaneous. The assay medium is incubated under conditions for binding of the capture agents to the target proteins. The substrate is then examined for the presence of the target proteins.

Abstract: Proteins in a sample are subjected to a computational digest to provide a set of predictive peptides for the protein. The predictive set of peptides are analyzed for their degree of prediction for the protein and rank-ordered to create a set of optimal predictor peptides. The optimal predictor peptides are then used to provide m/z ranges to the control software for the mass spectrometer to use as recommendations for ion selection for second stage analysis.

Abstract: Compounds, compositions, methods for sequencing proteins and peptides, and methods for identifying proteins and peptides in a mixture, are disclosed. Compounds of formula A-B-C wherein A is a nucleophilic reactive group, B is a detectable moiety capable of being isotopically labeled, and C is a charge replacement group, are used to label the peptides at the N-terminus or the C-terminus. The tagged peptides can then be analyzed by mass spectroscopy.