Untargeted metabolic fingerprinting of MMV compounds on intracellularly treated T. gondii parasites
Ontology highlight
ABSTRACT:
INSTRUMENT(S): Q Exactive Plus
ORGANISM(S): Toxoplasma Gondii (ncbitaxon:5811) Homo Sapiens (ncbitaxon:9606)
SUBMITTER: 
Martin Blume
PROVIDER: MSV000093444 | MassIVE | Tue Nov 21 06:10:00 GMT 2023
REPOSITORIES: MassIVE
Similar Datasets
Project description:HFF cells were infected with PruTom at MOI 1. Intracellular parasites were treated with Atovaquone, Buparvaquone, or MMV1028806 and incubated for three hours with DMEM containing 4 mM 15N-amide-glutamine instead of the respective unlabeled carbon sources. Cultures were quenched in ice-cold PBS and parasites were isolated from their host cells by passaging scraped monolayers through a 23 G needle, filtered through a 3 um polycarbonate filter and after microscopic counting distributed at 1 x 108 parasites per sample. Parasites were washed with ice-cold PBS via 5 min centrifugation at 21'500 x g at 0 degrees. Metabolites were then extracted by sonication for 2 min in 50 uL 80 percent acetonitrile in water. The insoluble particles were pelleted for 5 min at 21,500 x g at 0 degrees. 5 uL of each sample was collected to generate a pooled biological quality control (PBQC) which was injected regularly into the otherwise randomized run list. 5 uL of each sample was injected onto either an ACQUITY UPLC BEH amide column (Waters) equipped with a VanGuard amide pre-column (Waters) or onto a SeQuant ZIC-pHILIC (Merck) column with an OPTI-LYNX ZIC-pHILIC guard column cartridge (Optimize Technologies) operating on a Vanquish Flex (Thermo Fisher). Analytes were chromatographically separated starting with 100 percent eluent A (90 percent acetonitrile in water with 10 mM ammonium carbonate) and 0 percent eluent B (10 mM ammonium carbonate in water), decreasing to 40percent A and 60percent B over 25 min. Metabolites were detected on a Q Exactive Plus (Thermo Fisher) equipped with an electrospray ionization source. To increase coverage of the isotopologues, metabolites were measured in positive and negative mode separately without MS2 scans but with an increased MS1 scan resolution of 140k.
2023-11-21 | MSV000093447 | MassIVE
Project description:HFF cells were infected with PruTom at MOI 1. Intracellular parasites were treated with Atovaquone, Buparvaquone, or MMV1028806 and incubated for three hours with DMEM containing either 25 mM U-13C-glucose or 4 mM 15N-amide-glutamine instead of the respective unlabeled carbon sources. Cultures were quenched in ice-cold PBS and parasites were isolated from their host cells by passaging scraped monolayers through a 23 G needle, filtered through a 3 um polycarbonate filter and after microscopic counting distributed at 1 x 108 parasites per sample. Parasites were washed with ice-cold PBS via 5 min centrifugation at 21'500 x g at 0 degrees. Metabolites were then extracted by sonication for 2 min in 50 uL 80 percent acetonitrile in water. The insoluble particles were pelleted for 5 min at 21,500 x g at 0 degrees. 5 uL of each sample was collected to generate a pooled biological quality control (PBQC) which was injected regularly into the otherwise randomized run list. 5 uL of each sample was injected onto either an ACQUITY UPLC BEH amide column (Waters) equipped with a VanGuard amide pre-column (Waters) or onto a SeQuant ZIC-pHILIC (Merck) column with an OPTI-LYNX ZIC-pHILIC guard column cartridge (Optimize Technologies) operating on a Vanquish Flex (Thermo Fisher). Analytes were chromatographically separated starting with 100 percent eluent A (90 percent acetonitrile in water with 10 mM ammonium carbonate) and 0 percent eluent B (10 mM ammonium carbonate in water), decreasing to 40percent A and 60percent B over 25 min. Metabolites were detected on a Q Exactive Plus (Thermo Fisher) equipped with an electrospray ionization source. To increase coverage of the isotopologues, metabolites were measured in positive and negative mode separately without MS2 scans but with an increased MS1 scan resolution of 140k.
2023-11-21 | MSV000093445 | MassIVE
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.
2014-02-14 | PXD000354 | Pride
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.
2014-01-09 | PXD000658 | Pride
Project description:Plasma proteome response to repeated ACTH administration in juvenile northern elephant seals. Five ul of EDTA plasma were denatured with 200 ul of 5 percent w/v SDC and 5 mM TCEP in 50 mM AmBiC at 60C for 1 hour, followed by alkylation with 20 mM CAA for 30 minutes in the dark at room temp. Samples were diluted to 0.5 percent SDC and proteins were digested using trypsin at a 1 to 50 ug enzyme to protein ratio for 16 hours at 37C. TFA was added to a final concentration of 1.0 percent to precipitate SDC, which was removed by centrifugation and extraction of the supernatant. Digested peptides were lyophilized, resuspended in 0.1 percent TFA, and desalted using Pierce Peptide Desalting Spin Columns. Eluted peptides were lyophilized and resuspended in 0.1 percent FA in LC-MS grade water.
Three injections were used for each sample. For each run, 5 uL of the sample (1 ug total) was loop injected onto a reversed-phase trap column (Acclaim PepMap 100 C18 LC column; 75 um i.d. x 2 cm, 3 um particle size, 100 A pore size, Thermo Fisher Scientific, USA) by a Dionex Ultimate 3000 autosampler. Peptides were eluted onto a reversed-phase analytical column set at 35C for HPLC (EASY-SprayTM C18 LC column; 75 um i.d. x 15 cm, 100 A, Thermo Fisher Scientific, USA). Solvent A was water and B was acetonitrile (ACN), respectively (both with 0.1 percent formic acid). During each chromatographic run, which lasted 140 min, flow rates were held at 300 nl/min. Solvent B (ACN) was used as follows: 2 percent at 5 min, 2-22 percent at 75 min, 22-38 percent at 100 min, 38-95 percent at 105 min, 95 percent returning to 2 percent at 115 min, and lastly maintained at 2 percent at 140 min.
Mass spectrometry analysis was performed using Orbitrap Fusion Tribrid mass spectrometer equipped with an EASY-SprayTM ion source and operated by Xcalibur 4.0 software. MS1 spectra were resolved by the orbitrap with a resolution of 120,000, scan range of 200-1400 m/z, RF lens of 60 percent, AGC target of 1.0e6, and max injection time of 50 ms. Precursor ions were isolated by quadrupole and fragmented using HCD with a collision energy of 28 percent. MS2 product ions were resolved by the orbitrap (resolution: 30,000, AGC target: 5.0e5, first mass: 100 m/z, and max injection time: 150 ms).
2024-08-02 | MSV000095508 | MassIVE
Project description:Immunoaffinity Purifications of Human Argonaute Twelve hours after transfections with mock or with miR-124, we washed each 15-cm plate once with phosphate-buffered saline (usually two plates were used per IP), then added 1 ml of 4 C lysis buffer (150 mM KCl, 25 mM Tris-HCl [pH 7.4], 5 mM Na-EDTA [pH 8.0], 0.5% Nonidet P-40, 0.5 mM DTT, 10 ul protease inhibitor cocktail [Pierce Cat# 78437], 100 U/ml SUPERaseIn [Ambion Cat# AM2694]). Following a 30-min incubation at 4 C, we scraped the plates, combined the lysates, and then spun them at 4 C for 30 min at 14,000 RPM in a microcentrifuge. We collected the supernatant and filtered it through a 0.45-um syringe filter. We froze an aliquot of lysate in liquid nitrogen for reference RNA isolation. We then added 0.22 mg/ml heparin to the lysate. We mixed the lysate with 2.5 mg of Dynal m-280 streptavidin beads (250 ul from original storage solution) coupled to biotinylated 4F9 ago antibody (~12.5 ug), which we equilibrated immediately prior to use by washing twice with 1 ml of lysis buffer. We incubated the beads with the lysate for 2 h at 4 C and then washed the beads twice with 1.25 ml of ice-cold lysis buffer for 5-min each. Five percent of the beads were frozen for SDS PAGE analysis after the second wash. RNA was extracted directly from the remaining beads using lysis buffer from Invitrogen's Micro-to-Midi kit (Invitrogen Cat# 12183-018). We purified RNA from the lysate and RNA extracted from the beads with the Micro-to-Midi kit as per vender's instructions, except that the percentage isopropanol used for binding to the column was 70%, instead of 33%, to promote the binding of small RNAs. RNA was amplified with ambion kit 1755. RNA from total cell lysate was labeled with cy3 and IPd RNA was labeled with cy5
2009-11-10 | GSE18834 | GEO
Project description:We reported that the microRNA profiling of exosome isolated from 58 cerebrospinal fluid (CSF) of 38 medulloblastoma (MBL) patient with or without letomeningeal metastases (LM). CSF exosome was precipitated using Exo2DTM for RNA assay (EXOSOME plus, Suwon, South Korea) according to the manufacture’s protocol (Kim, et al. 2017). 2 ml of CSF were added to Exo2DTM reagent B following mixing by inverting, and incubated at room temperature for 30 min. The supernatant was discarded and the exosome containing pellet was resuspended in 100 ul of PBS to further RNA isolation. Total RNA was extracted from the CSF exosome fraction using a microRNA purification kit (Norgen Biotek corp., Thorold, Canada) according to the manufacture’s protocol. Briefly, samples were mixed with lysis buffer, and the lysate was added to absolute ethanol. The lysate was applied up to the column and centrifuged at 8,000 rpm for 1 min. The column was washed with wash solution and centrifuged at 14,000 rpm for 1 min. Finally, the column was applied to 20 ul of elution solution and centrifuged at 14,000 rpm for 2 min, and the flow-through was stored at –80 ℃ for storage. RNA precipitates were quantified and qualified with Bioanalyzer Pico 6000 Chip (Agilent Technologies, Santa Clara, CA). The 10 ng of total RNA was provided to the cDNA library generation using SMARTer smRNA-Seq kit (Illumina Inc., San Diego, CA), according to the user manual. The cDNA library was subjected to sequencing using Truseq SBS Kit and HiSeq 2500 System (Illumina Inc., San Diego, CA), according to user guide.
2020-09-15 | GSE157916 | GEO
Project description:Proteomic analysis Epilepsy was induced using perforant pathway stimulation (PPS) in rats as described (Norwood BA, et al. (2010) Classic hippocampal sclerosis and hippocampal-onset epilepsy produced by a single "cryptic" episode of focal hippocampal excitation in awake rats. J Comp 803 Neurol 518(16):3381-3407). Rats were killed under deep anesthesia (xylazine+ketamine) by transcardial perfusion with ice-cold 0.9 % NaCl solution at the following time points: 1 h, 24 h, 72 h, 10 d and 16 d after PPS (epileptogenesis); within 1 d of first spontaneous seizure (early epilepsy); 1 month after first spontaneous seizure (chronic epilepsy). Control rats were killed on day 17 after surgery (corresponding to day 10 after PPS). Hippocampi were removed and snap frozen at -80°C. Frozen rat hippocampi were resuspended in 200 ul lysis buffer (6M GdmCl, 10mM TCEP, Complete protease inhibitor cocktail, PhosSTOP inhibitor, 100 mM TEAB, benzonase) and dounced 30 times on ice. Samples were boiled for 5 min, sonicated on ice for 2min and centrifuged at 13000 rpm for 3 min. The supernatant was added chloroacetamide to a final concentration of 20 mM followed by incubation in the dark for 30 min at room temperature (RT). Proteins were digested with LysC for 30 min at RT and then diluting 10x— using 100 mM TEAB followed by adding trypsin and incubating overnight at 37°C with shaking. LysC and trypsin were added in a LysC/trypsin:protein ratio of 1:100. Samples were centrifuged at 13000 rpm for 5 min and from the supernatant a volume corresponding to 50 ug peptide was transferred to a new eppendorff tube. Sets of 6 samples were labelled using the TMTsixplex isobaric label reagent. (ThermoFisher Scientific). The labeling reagent was prepared using the manufactures instructions to first equilibrate to RT, then dissolving the labeling reagent in 41 ul anhydrous acetonitrile. The labeling reagent was added to each sample and incubated for 1 hour at RT. The reaction was quenched by incubating with 0.76 M lysine for 15 min. A small amount was taken from each sample, mixed and tested by mass spectrometry for labeling efficiency and mixing ratio. Remaining samples were mixed in a 1:1 ratio. The Stage-tips for the high-pH reverse phase fractionation were prepared by placing first two C18 disks in a p200 pipette tip, then adding a slurry of C18 beads (ReproSil-Pur, 3 um) in methanol and adding one additional C18 disk in the top. The column was activated and equilibrated by washing one time in 150 ul buffer B (50% buffer A, 50% ACN) and then two times in 150 ul buffer A (20mM Ammonium hydroxide, pH 10). The labeled peptide sample was adjusted to pH 10 using buffer A and then loaded onto the activated and equilibrated stage-tip by spinning the sample through the column and collecting 26 the flow-through. The column was washed 2 times with 150 ul buffer 585 A and the washes were collected and combined with the flow-through. Next, peptides were eluted stepwise in 17 fractions by spinning 150 ul of buffer A containing increasing amounts of ACN for each step (3.5%, 4.5%, 6%, 8%, 10%, 10.5%, 11.5%, 13.5%, 15%, 16%, 17.5%, 18.5%, 19.5%, 21%, 27%, 50%, 80%) through the column. After collection, the liquid was evaporated completely in a Concentrator Plus (Eppendorf) and prepared for MS by resuspending in buffer A* (2% ACN, 0.1% TFA). Samples were analyzed using an Easy-nLC system coupled online to a Q Exactive HF mass spectrometer (Thermo Scientific) equipped with a nanoelectrospray ion source (Proxeon/Thermo Scientific). The peptides were eluted into the mass spectrometer during a chromatographic separation from a fused silica column packed in-house with 3 um C18 beads (Reprosil, Dr. Maisch) using a 120 min gradient of buffer B (80% ACN, 0.5% acetic acid) with a flow rate of 250 nL/min. The Q Exactive HF was operated in positive ion mode with a top 12 data-dependent acquisition method where ions were fragmented by higher-energy collisional dissociation (HCD) using a normalized collisional energy (NCE)/ stepped NCE of 28 and 32. The resolution was set to 60,000 (at 400m/z), with a scan range of 300-1700 m/z and an AGC target of 3e6 for the MS survey. MS/MS was performed at a scan range of 100 - 2000 m/z using a resolution of 30,000 (at 400 m/z), an AGC target of 1e5, an intensity threshold of 1e5 and an isolation window of 1.2 m/z. Further parameters included an exclusion time of 45 sec and a maximum injection time for survey and MS/MS of 15 ms and 45 ms respectively.
2020-06-12 | PXD019098 | Pride
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
2014-04-28 | PXD000505 | Pride
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
2014-04-28 | PXD000504 | Pride