ABSTRACT: Data set for demonstration of rawDiag package functions.
LC-MS data was recorded on a Q Exactive HF-X (Thermo Fisher Scientific) operated in line with an Acquity M-Class (Waters) UPLC. In short, peptides were loaded onto a nanoEase M/Z Symmetry C18 100A, 5 um, 180 um x 20 mm trap column (Waters, part# 186008821) and separated running a peace-wise linear gradient from 5% to 24% B in 50 min and 24% to 36% B in 10 min over the nanoEase M/Z C18 T3 Col 100A, 1.8 um, 75 um x 250 mm analytical column (Waters, part# 186008818) at a flow rate of 300 nl/min (buffer A: Water incl. 0.1% formic acid; buffer B: acetonitrile incl. 0.1% formic acid). Eluting peptides were ionized applying the principle of electro spray ionization on a Digital PicoView 550 (New Objective) nano source equipped with silica emitters (New Objective, part# FS360-20-10-N-20-C12 DOM). Data dependent analysis (DDA) was conducted by recording MS1 spectra at 60k R over the scan range of 350 to 1400 m/z. MS2 scans were acquired at 7500 R (AGC target: 1e5, maxIT: 11 ms) for the most abundant (topN: 36, 48 or 72) precursor signals using an isolation window of 1.3 Da and a NCE of 28 for peptide fragmentation. Dynamic exclusion was set to 10 s. Ions having a charge below 2 and above 6, as well as isotopes were excluded from further analysis.
Project description:Female Sprague-Dawley rats were randomly separated into two groups: i) trained (Ex group) and ii) sedentary (Cont group). Animals from the Ex group were adapted to treadmill exercise for two consecutive weeks, involving a gradual increase in the running time till 60 min/day at 20 m/min, 0% grade, 5 days/week. This exercise program remained constant until the end of the 54 weeks. Mitochondria isolation from 10 animals (5 Ex group and 5 Cont group) was performed using the conventional methods of differential centrifugation. Mitochondrial protein extracts were reduced with dithiothreitol, alkylated with iodoacetamide and digested with trypsin using the FASP procedure (18). Briefly, each sample was solubilized in 4 % SDS, 0.1 M DTT, 0.1 M HEPES and incubated for 30 min at 60 C. Then, samples were mixed with 0.2 mL of a solution of 8 M Urea, 0.1 M HEPES, pH 8.5 (UH solution), loaded into the filtration devices (3k Microcon, Millipore), centrifuged at 14,000 g for 20 min, and washed twice with UH solution. After centrifugation, the concentrates were alkylated with 50 mM iodoacetamide in UH solution (dark, 25 C, 20 min), and washed twice with UH solution. The concentrate was diluted with 0.1 mL of 50 mM ammonium bicarbonate (ABC) and digested overnight (37 C) with the addition of 2 ug of trypsin diluted in 30 uL of 50 mM ABC. The resulting tryptic peptides were collected by centrifugation and the filter were washed twice with 50 uL of 50 mM ABC. Eluted peptides were acidified with 10 uL of formic acid and cleaned up on a homemade Empore C18 column (3M, St. Paul, MN, USA) (ref) for subsequent phospho-enrichment and/or analysis by LC-MS/MS. The dried protein digest was dissolved with 10 uL (3 % ACN, 0.1 % TFA), diluted 1:5 with loading buffer (1 M glycolic acid, 5 % TFA, 80 % ACN) and phosphopeptides were enriched on TiO2-beads as previously described (19). Briefly 5 mg of "Titansphere TiO2 5 um" were suspended in 100 uL of 100 % ACN, immobilized in a pipette-column and washed using 5 uL of loading buffer. Each sample was loaded in each pipette-column and then washed with 30 uL of washing buffer (1 % TFA, 80 % ACN). Phosphopeptides were eluted from the beads with 25 uL of 25 % ACN (v/v) containing 25 % NH4OH (m/v), acidified with 10 uL of 10 % TFA and vacuum- concentrated to approximately 4 uL. Samples were finally diluted to 10 uL with H2O + 0.1% formic acid prior to injection. The peptides mixtures were analyzed by online nanoflow liquid chromatography tandem mass spectrometry (nanoLC-MS/MS) on an EASY-nLC system (Proxeon Biosystems, Odense, Denmark) connected to the LTQ Orbitrap Velos instrument (Thermo Fisher Scientific, Bremen, Germany) through a nanoelectrospray ion source. Six microliters of the peptide mixture were auto-sampled directly onto the analytical HPLC column (120 mm x75 um I.D., 3 um particle size (Nikkyo Technos Co., Ltd.) with a 120-min gradient from 5 % to 50 % ACN in 0.1 % FA. The effluent from the HPLC column was directly electrosprayed into the mass spectrometer. The LTQ Orbitrap Velos instrument was operated in data-dependent acquisition mode to automatically switch between full scan MS and MS/MS acquisition. The MS survey scan was performed in the FT cell recording a window between 350 and 2000 m/z. The resolution was set to 60 000, and the automatic gain control was set to 1,000,000 ions with a maximal acquisition time of 400 ms. The 20 most intense peptide ions with charge states great than or equal to 2 were sequentially isolated to a target value of 5,000 and fragmented in the high-pressure linear ion trap by low-energy CID with normalized collision energy of 35% Q value of 0.25, and an activation time of 10 ms. Raw files were processed using Proteome Discoverer version 1.3 (Thermo Fisher Scientific, Bremen). Peak lists were searched using Mascot software version 2.3 (Matrix Science, UK) against a SwissProt database containing entries corresponding to Rattus norvegicus (version of July 2012), a list of common contaminants, and all the corresponding decoy entries. Trypsin was chosen as enzyme and a maximum of two miscleavages were allowed. Carbamidomethylation (C) was set as a fixed modification, whereas oxidation (M) and phosphorylation (STY) were used as variable modifications. Searches were performed using a peptide tolerance of 7 ppm, a product ion tolerance of 0.5 Da. Resulting data files were filtered for FDR less than 1 % at peptide level.
Project description:Prefrontal cortex tissue slices from a cognitively and neurpathologically normal human subject were obtained from the University of Pennsylvania (UPenn) Brain Bank. 300-350 mg grey matter was homogenized in 1.5 ml solution A (0.32 M sucrose, 1mM MgCl2 and 0.1mM CaCl2) with a Teflon pestle. ~100 ?l of the homogenate was saved, solubilized with 1% SDS and clarified by centrifugation. To prepare the [13C6]brain ISTD, 400 mg labeled MouseExpress brain tissue (Cambridge Isotopes, MA) was homogenized in 4 ml buffer A as described above, centrifuged at 1,000 x g for 10 min to clarify, agitated on a rocker at 4�C for 30 min, and centrifuged at 10,000 x g for 20 min. The pellet, a crude membrane fraction, was dissolved in 2 ml 20 mM Tris pH 7.4 with 1% SDS. Total protein in all preparations was quantified with the micro BCA assay (Pierce) and all solutions were supplemented with protease and phosphate inhibitor cocktails (Sigma) as well as 1 mM sodium fluoride and sodium orthovanadate (Sigma). Human cortex homogenate was mixed with the [13C6]brain ISTD (1?g/?l) at a ratio of 2:1(?g/?g) and processed for LC-MS/MS: 40 ?l preparations were heated with lithium dodecyl sulfate (LDS) (Invitrogen) buffer at 95�C for 20 min, separated on a 1.5 mm 4-12% Bis-Tris Gel (Invitrogen), cut into five fractions, chopped into ?2 mm cubes, washed in 200 ?l 50% acetonitrile (ACN) containing 25 mM NH4HCO3, reduced in 300 ?l 10 mM DTT, alkylated in 300 ?l 55 mM iodoacetamide (Sigma), and digested with 80-120 ?l trypsin (.025 ?g/?l) (Promega) overnight at 37�C, so that the amount of trypsin was 1:5 of the total protein to be digested by mass. Peptides were recovered from gel cubes into 200 ?l 50/50 H2O/ACN with 3% formic acid by vortex-mixing and sonication for 20 min each, twice. Samples were then evaporated to a 100 ?l volume, brought to 1ml in H20 with 0.1% formic acid, desalted with Oasis� HLB cartridges (Waters), evaporated almost to completion and suspended in ~ 45?l H2O with 0.1% formic acid, and filtered with 0.22 �m Ultra free-MC filter cartridges (Millipore). LC-data dependant -MS/MS analyses were conducted on a Q Exactive (ThermoFisher Scientific) quadrupole orbi-trap hybrid instrument with an Easy nLC-II (ThermoFisher Scientific) nano-pump/autosampler. 3?l peptide sample (~ 1 ug) was loaded and resolved on a 20 cm x 75 �m proteopepII C18 packed tip column over a 90 min gradient at a flow rate of 350 nL/min, 0-35% mobile phase B (ACN, 0.1 formic acid). A data-dependent top 10 method was used to acquire a 70,000 resolution full scan to trigger ten 17,500 resolution HCD scans. Ions were isolated for MS/MS analysis with a 2.0 Da window on the quadrupole. Average cycle times were 1.2 sec. Each sample was analyzed in triplicate. Raw files from triplicate injections were searched together within Proteome Discoverer 1.3 (ThermoFisher Scientific) using SEQUEST and the human refseq. database (release 47, ftp://ftp.ncbi.nih.gov/refseq/H_sapiens/mRNA_Prot/). Search parameters allowed trypsin to cleave after Lysine and Arginine and have 2 missed cleavages. Precursor ion mass tolerance was set to 15 ppm and fragment ion mass tolerance was 20 mmu. The dynamic modification of methionine (oxidation = 15.995 Da) and lysine (13C6 = 6.020 Da), in addition to the static modification of cysteine (carbamidomethylation = 57.021 Da) was accepted on up to 4 residues per peptide. Within the Proteome Discoverer Software, SILAC pairs were identified using the �2 plex� workflow node, and all peptides were rescored using the Percolator algorithm node. Finally, peptides were filtered at 1% false discovery rate (FDR).
Project description:Proteomic analysis of pervanadate-induced tyrosine-phosphorylated proteins in hepatocellular carcinoma WRL 68 cells Protein tyrosine phosphorylation plays critical roles in modulating biological processes such as cellular proliferation, differentiation, migration, apoptosis and metabolism. To profile tyrosine phosphorylated (pTyr) proteins as well as search novel pTyr proteins as cross-talk points among different cellular pathways, we developed a rapid and efficient approach to identify cellular pTyr proteins and their complexes by a combination of subcellular proteomics approach with signal transduction strategies. Human hepatocytic cells from WRL68 cell line were treated with pervanadate (POV), subfractionated into four fractions and then subjected to immunoaffinity purification with anti-pTyr antibody. The eluted mixtures of the anti-pTyr purification were identified by LC-MS/MS. Subcellular fractionation and affinity purification of tyrosine-phosphorylated proteins: WRL68 cells were first grown to 80% confluence in MEM complete medium and then the medium replaced with serum free media. After 15 h, the cells were either untreated or stimulated with 0.1 mM pervanadate (1 mM sodium orthovanadate, 3 mM H2O2) for 10 min. 150-mm cultures of WRL 68 cells were rinsed twice with 4? PBS and then scraped from the dish in 750?l of hypotonic buffer (10 mM Tris, 1 mM NaF, 10 mM IAA, pH 7.5) containing a cocktail of protein inhibitors. After a 20-min incubation on ice, the cells were passed about five times through a 25-g needle. The resulting lysate was subjected to a 15min centrifugation at 1000 rpm at 4?, after which the pellet was resuspended in 250?l of hypotonic buffer and re-extracted by a second round of the trituration and centrifugation. The supernatants of the first and second spins were combined, adjusted to 0.25 M NaCl, and separated into cytosolic (supernatant) and membrane (pellet) fractions bycentrifugation at 19,000 rpm (43,000 g) for 90 min at 4?. All the pellets and total cell lysate were resuspended in RIPA buffer (50 mM Tris-HCl, 150 mM NaCl, 1% Triton X-100, 0.1% SDS, 1% deoxycholic acid sodium) containing 1mM pervanadate with a cocktail of protein inhibitors with sonication aid. Cleared cell lysates were incubated overnight at 4? with 30?l monoclonal anti-phosphotyrosine-agrose (Sigma). Precipitated immune complexes were washed three times with 1×HNTG (20 mM HEPES, 150 mM NaCl, 0.1% Triton X-100, 10% Glycerol, pH 7.5) and then eluted with 100 mM phenyl phosphate (Sigma) in lysis buffer at 4?. Enzyme digestion, mass spectrometry and protein identification: The sample was digested according to the published method. Chromatography was performed using a surveyor LC system (Thermo Finnigan,SanJose,CA) on C18 reverse phase column(RP, 180 µm x 150 mm, BioBasic® C18, 5 µm, Thermo Hypersil-Keystone). The pump flow rate is split 1:100 for a colum flow rate of 1.5 µL/min.The column effluent is directly electrosprayed using the orthogonal metal needle source without further splitting.Mobile phase A is 0.1% formic acid in water,and the B mobile phase is 0.1% formic acid in acetonitrile. The separation of peptides obtained by enzymatic digest of bile sample was achieved with a gradient of 2-80% B over 360 min.The column effluent from the reverse phase column was analyzed by LCQ Deca XP ion-trap mass spectrometer.The micro-electrospray interface uses a 30 µm metal needle that is orthogonal to the inlet of the LCQ.The mass spectrometer was set that one full MS scan was followed by three MS/MS scans on the three most intense ion from the MS spectrum with the following Dynamic Exclusion™ settings: repeat count, 1; repeat duration, 0.5 min; exclusion duration, 3.0 min. The acquired MS/MS spectra were automatically searched against protein database for human proteins (SWISS-PROT/TrEMBL) using the TurboSEQUEST program in the BioWorks™ 3.0 software suite. An accepted SEQUEST result had to have a ?Cn score of at least 0.1 (regardless of charge state) and Xcorr (one charge?1.5, two charges?2.0, three charges?2.5). Single peptides that alone identify a protein were manually validated after meeting the above criteria. Bioinformatics analysis: The pI and MW of the proteins were analyzed using ExPASy proteomics tools accessed from http://cn.expasy.org/tools/#proteome. The grand average hydropathicity (GRAVY) values were determined according to Kyte-Doolittle. The protein subcellular location annotation was from SwissProt &TrEMBL protein database (http://us.expasy.org/sprot/). The protein function family was categorized according to Gene Ontology (GO) annotation terms extracted by InterPro (http://www.ebi.ac.uk./interpro/). The annotation of protein phosphorylation was from SwissProt &TrEMBL protein database (http://us.expasy.org/sprot/) and PhosphoSite (http://www.phosphosite.org). The kinases were annotated according to human kinome. Keywords: other
Project description:Fecal samples of C57BL/6 mice exposed to relevant levels of cadmium and arsenic over two weeks in the drinking water. Sample types include controls, arsenic and cadmium groups. The samples were analyzed by liquid chromatography tandem mass spectrometry (LC-MS/MS) and data was recorded in a data dependent manner, on a Q-Exactive (Thermo scientific, Bremen, Germany). An EASY nLC-1000 liquid chromatography system (Thermo scientific, Odense, Denmark) was coupled to the mass spectrometer through a 2 cm C18 pre-column (300 um inner diameter and 1.9 um particle size) and a self-packed 15 cm (Pico Frit columns from New Objective with a 75 um inner diameter, packed with ( 1.9um C18 Dr Maisch Mat. No. r119.a). Metabolites were eluted with a mobile phase consisting of solvent A (0.1% formic acid) and B (80% acetonitrile in 0.1% formic acid). The concentration of solvent B was linearly increased from 2-10% over 3 min and from 10-95% solution B over 15min. Solvent B was maintained at 95% for 2 min. Full scans were acquired in the Orbitrap with a resolution of 70000, maximum injection time of 20 ms and a scan range of 80-1200 m/z using a Top 10 method with an isolation window of 1.6 Da and a dynamic exclusion time of 15 sec. For the MS/MS scans the resolution was adjusted to 17500 and maximum injection time of 60 ms. Ions were fragmented in a higher-energy collision dissociation (HCD) cell with normalized collision energy (NCE) of 30%.
Project description:Cervicovaginal lavage (CVL)supernatants were heat inactivated for 30 minutes at 56°C before further processing. Total protein concentrations were determined using the Pierce Coomassie Plus (Bradford) Protein Assay (Thermo Scientific, Rockford, IL, USA). Sample protein content and volume were normalised with 25mM ammonium bicarbonate (ABC). Soluble proteins were precipitated using an equal volume of ice cold 30% (w/v) TCA in acetone and incubated at -20⁰C for 2 hours. Samples were centrifuged at 12,000g for 10 minutes (4⁰C) to pellet proteins. Pellets were washed three times with ice cold acetone and allowed to air dry. Further sample processing was performed as previously described (Armstrong et al, 2014) with minor modifications. Briefly, protein pellets were resuspended in 25 mM ABC, 0.05%(w/v) rapigest (Waters), reduced and alkylated. Digestion was performed with proteomic-grade trypsin (Sigma-Aldrich, St. Louis, MO, USA) at a protein:trypsin ratio of 50:1. Rapigest was precipitated by addition of trifluoroacetic acid to a final concentration of 0.5% (v/v). Peptide mixtures were analyzed by on-line nanoflow liquid chromatography using the nanoACQUITY-nLC system (Waters MS technologies) coupled to an LTQ-Orbitrap Velos (ThermoFisher Scientific, Bremen, Germany) mass spectrometer equipped with the manufacturer’s nanospray ion source. The gradient of the analytic column (nanoACQUITY UPLCTM BEH130 C18 15cm x 75µm, 1.7µm capillary column) consisted of 3-40% acetonitrile in 0.1% formic acid for 90 min then a ramp of 40-85% acetonitrile in 0.1% formic acid for 5min.
Project description:Bacteria were washed three times in NaCl (150 mM). Cells were resuspended in 1 ml TSU buffer (50 mM Tris pH 8.0, 0.1% SDS, 2.5 M urea) and lysed by two freeze-thaw cycles in liquid nitrogen. Lysate proteins (40 ug) were separated and digested. Digested peptides were separated by nano-LC using an Ultimate 3000 HPLC and autosampler system (Dionex; Amsterdam, Netherlands). Samples (1 ul) were concentrated and desalted onto a micro C18 pre-column (500 um×2 mm, Michrom Bioresources; Auburn, CA, USA) with H2O:CH3CN (98:2, 0.05% trifluoroacetic acid) at 15 ul min−1. After a 4 min wash the pre-column was switched (Valco 10 port valve; Dionex) into line with a fritless nano column (75 u×~10 cm) containing C18 media (5 u, 200 A Magic; Michrom) manufactured according to Gatlin. Peptides were eluted using a linear gradient of H2O:CH3CN (98:2, 0.1% formic acid) to H2O:CH3CN (64:36, 0.1% formic acid) at 250 nl min−1 over 30 min. High voltage (2000 V) was applied to low volume tee (Upchurch Scientific) and the column tip positioned ~0.5 cm from the heated capillary (T = 280 degrees C) of an Orbitrap Velos (Thermo Electron; Bremen, Germany) mass spectrometer. Positive ions were generated by electrospray and the Orbitrap operated in data dependent acquisition mode (DDA). A survey scan m/z 350–1750 was acquired in the Orbitrap (Resolution = 30,000 at m/z 400, with an accumulation target value of 1,000,000 ions) with lockmass enabled. Up to the 10 most abundant ions (>5,000 counts) with charge states >+2 were sequentially isolated and fragmented within the linear ion trap using collisionally induced dissociation with an activation q = 0.25 and activation time of 30 ms at a target value of 30,000 ions. M/z ratios selected for MS/MS were dynamically excluded for 30 s. Peak lists were generated using Mascot Daemon/extract_msn (Matrix Science, Thermo; London, England) using the default parameters, and submitted to the database search program Mascot (version 2.1, Matrix Science). Search parameters were: Precursor tolerance 4 ppm and product ion tolerances +/-0.4 Da; Oxidation (M) and Carbamidomethyl (C) specified as variable modifications, Enzyme specificity was trypsin, 1 missed cleavage was possible
Project description:Washed three times in NaCl (150 mM). Cells were resuspended in 1 ml TSU buffer (50 mM Tris pH 8.0, 0.1% SDS, 2.5 M urea) and lysed by two freeze-thaw cycles in liquid nitrogen. Lysate proteins (40 ug) were separated and digested. Digested peptides were separated by nano-LC using an Ultimate 3000 HPLC and autosampler system (Dionex; Amsterdam, Netherlands). Samples (1 ul) were concentrated and desalted onto a micro C18 pre-column (500 um×2 mm, Michrom Bioresources; Auburn, CA, USA) with H2O:CH3CN (98:2, 0.05% trifluoroacetic acid) at 15 ul min−1. After a 4 min wash the pre-column was switched (Valco 10 port valve; Dionex) into line with a fritless nano column (75 u×~10 cm) containing C18 media (5 u, 200 A Magic; Michrom) manufactured according to Gatlin. Peptides were eluted using a linear gradient of H2O:CH3CN (98:2, 0.1% formic acid) to H2O:CH3CN (64:36, 0.1% formic acid) at 250 nl min−1 over 30 min. High voltage (2000 V) was applied to low volume tee (Upchurch Scientific) and the column tip positioned ~0.5 cm from the heated capillary (T = 280 degrees C) of an Orbitrap Velos (Thermo Electron; Bremen, Germany) mass spectrometer. Positive ions were generated by electrospray and the Orbitrap operated in data dependent acquisition mode (DDA). A survey scan m/z 350–1750 was acquired in the Orbitrap (Resolution = 30,000 at m/z 400, with an accumulation target value of 1,000,000 ions) with lockmass enabled. Up to the 10 most abundant ions (>5,000 counts) with charge states >+2 were sequentially isolated and fragmented within the linear ion trap using collisionally induced dissociation with an activation q = 0.25 and activation time of 30 ms at a target value of 30,000 ions. M/z ratios selected for MS/MS were dynamically excluded for 30 s. Peak lists were generated using Mascot Daemon/extract_msn (Matrix Science, Thermo; London, England) using the default parameters, and submitted to the database search program Mascot (version 2.1, Matrix Science). Search parameters were: Precursor tolerance 4 ppm and product ion tolerances +/-0.4 Da Oxidation (M) and Carbamidomethyl (C) specified as variable modifications Enzyme specificity was trypsin, 1 missed cleavage was possible
Project description:Four bile samples collected from patients with a malignant (PAC, CC) or a nonmalignant (CP, BS) biliary stenosis were used for comparative proteomic analysis. Briefly, bile samples were centrifuged at 16,000/g/ for 10 min at 4 C. Each supernatant was delipided with Cleanascite (Biotech Support Group, North Brunswick, NJ, USA) and ultrafiltrated using a 3 kDa filter cut-off (YM-3 centricon, Millipore, Bedford, MA, USA). For each sample, 50 ug of proteins were mixed with 0.5 M triethylammonium bicarbonate (TEAB) buffer pH 8.0 to a total volume of 100 uL. One ug of bovine lactoglobulin (LACB) was spiked in each sample as an internal standard. Proteins were reduced and alkylated before digestion of N-linked oligosaccharides from glycoproteins using PNGase F (Sigma-Aldrich, St. Louis, MO, USA). Proteins were then digested with trypsin and the resulting peptides were tagged with one of the isobaric tags from the iTRAQ reagents 4plex kit (AB Sciex, Foster City, CA, USA) according to the manufacturer's instructions. The four samples were then pooled and dried under vacuum. Labeled peptides were fractionated according to their isoelectric point on an Agilent 3100 OFFGEL fractionator using 24 cm pH 3-10 linear immobilized pH gradients (GE Healthcare, Chalfont St. Giles, UK) following manufacturer's instructions. Fractions were then recovered in separate tubes for high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). MS analysis was performed on a LTQ Orbitrap XL from Thermo Electron (San Jose, CA, USA) equipped with a NanoAcquity HPLC system from Waters. Peptides were trapped on a home-made 5 um 200 A Magic C18 AQ (Michrom, Auburn, CA, USA) 0.1 x 20 mm pre-column and separated on a home-made 5 um 100 A Magic C18 AQ (Michrom) 0.75 x 150 mm column with a gravity-pulled emitter. The analytical separation was run for 65 min using a gradient of H_2 O/formic acid (FA) 99.9%/0.1% (solvent A) and CH_3 CN/FA 99.9%/0.1% (solvent B). The gradient was run at a flow rate of 220 nL/min as follows: 5% B for 1 min, from 5 to 35% B in 54 min, from 35 to 80% B in 10 min. For MS survey scans, the OT resolution was set to 60,000 and the ion population was set to 5 x 10^5 with an m/z window from 400 to 2000. Maximum of 3 precursors were selected for both collision-induced dissociation (CID) in the LTQ and high-energy C-trap dissociation (HCD) with analysis in the Orbitrap (OT). For MS/MS in the LTQ, the ion population was set to 1 x 10^4 (isolation width of 2 m/z) while for MS/MS detection in the OT, it was set to 2 x 10^5 , with resolution of 7,500, first mass at m/z = 100, and maximum injection time of 750 ms. The normalized collision energies were set to 35% for CID and 60% for HCD. Peak lists from MS analysis were searched against Uniprot_Swissprot database (version 2011_2) using Phenyx protein identification software (GeneBio, Geneva, Switzerland). /Homo Sapiens/ taxonomy was specified for database searching. The parent ion tolerance was set to 10 ppm. Variable amino acid modifications were oxidized methionine and deamidated asparagine. Carbamidomethylation of cysteines and iTRAQ-labeled peptides on the amino terminus and lysine were set as fixed modifications. Trypsin was selected as the enzyme, with one potential missed cleavage, and the normal cleavage mode was used. Only one search round was used with selection of "turbo" scoring. The peptide p value was 10^-2 for LTQ-OT data. Protein and peptide scores were set up to maintain the false positive rate below 5%.
Project description:Ammonium hydroxide and pyrrolidine eluents were dried (SpeedVac) and reconstituted in 25 ul sample loading buffer (0.1% TFA/2% acetonitrile). Eluent from phosphotyrosine immunoprecipitation was dried and reconstituted in 35 ul of the loading buffer. An LTQ Orbitrap XL (ThermoFisher) in-line with a Paradigm MS2 HPLC (Michrom bioresources) was employed for acquiring high-resolution MS and MS/MS data. Ten microliters of the phospho-enriched peptides were loaded onto a sample trap (Captrap, Bruker-Michrom) in-line with a nano-capillary column (Picofrit, 75 um i.d.x 15 um tip, New Objective) packed in-house with 10 cm of MAGIC AQ C18 reverse phase material (Michrom Bioresource). Two different gradient programs, one each for MOAC and phosphotyrosine immunoprecipitation samples, were used for peptide elution. For MOAC samples, a gradient of 5-40% buffer B (95% acetonitrile/1% acetic acid) in 135 min and 5 min wash with 100% buffer B followed by 30 min of re-equilibration with buffer A (2% acetonitrile/1% acetic acid) was used. For phosphotyrosine immunoprecipitation samples, which were a much less complex mixture of peptides, 5-40% gradient with buffer B was achieved in 75 min followed by 5 min wash with buffer B and 30 min re-equilibration. Flow rate was ~0.3 ul/min. Peptides were directly introduced into the mass spectrometer using a nano-spray source. Orbitrap was set to collect 1 MS scan between 400-2000 m/z (resolution of 30,000 @ 400 m/z) in orbitrap followed by data dependent CID spectra on top 9 ions in LTQ (normalized collision energy ~35%). Dynamic exclusion was set to 2 MS/MS acquisitions followed by exclusion of the same precursor ion for 2 min. Maximum ion injection times were set to 300 ms for MS and 100 ms for MS/MS. Automatic Gain Control (AGC) was set to 1xe6 for MS and 5000 for MS/MS. Charge state screening was enabled to discard +1 and unassigned charge states. Technical duplicate data for each of the MOAC elutions (ammonium hydroxide and pyrrolidine) and triplicate data for the phosphotyrosine immunoprecipitation samples were acquired. RAW files were converted to mzXML using msconvert and searched against the Swissprot Human protein database (2013-Jan release) appended with common proteomics contaminants and reverse sequences as decoys. Searches were performed with X!Tandem (version 2010.10.01.1) using the k-score plugin. For all searches the following search parameters were used: Parent monoisotopic mass error of 50 ppm; fragment ion error of 0.8 Daltons; allowing for up to 2 missed tryptic cleavages. Variable modifications were oxidation of Methionine (+15.9949@M), carbamidomethylation of Cysteine (+57.0214@C), and phosphorylation of Serine, Threonine, and Tyrosine (+79.9663@[STY]). The search results were then post-processed using PeptideProphet and ProteinProphet.