Top-down proteomics of mouse beta cell carboxypeptidase E deletion reveals novel substrates and defects in hormone processing
Ontology highlight
ABSTRACT:
INSTRUMENT(S): Orbitrap Fusion Lumos
ORGANISM(S): Mus Musculus (ncbitaxon:10090)
SUBMITTER: 
Wei-Jun Qian
PROVIDER: MSV000092097 | MassIVE | Sun Jun 04 21:33:00 BST 2023
REPOSITORIES: MassIVE
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Project description:MicroPoly(A)Pure kits (Ambion) were used to prepare mRNA from P. salmonis-infected and control Atlantic salmon head kidney. Head kidney mRNA samples were prepared from pooled (n = 10) infected or control kidney. Approximately 200 ng of infected or control head kidney mRNA was used as template in aRNA synthesis reactions. Two infected head kidney samples were pooled to yield 8.9 ug of aRNA, and a single control head kidney sample contained 8.4 ug of aRNA. Infected and control head kidney aRNA samples were visualized on agarose gels to check quality and quantity (data not shown). Except for the amounts of aRNA and reverse transcription (RT) primer used, head kidney target labeling reactions and microarray hybridizations were identical. Head kidney target syntheses used 2 ug of aRNA and 2 ug of random primers (Roche). RT primers were mixed with aRNA samples, and nuclease-free H2O (Invitrogen) was added to make 10 ul total volume. Samples were incubated at 70 degrees C for 4 min, then placed on ice. RT reactions included 50 mM Tris HCl pH 8.3, 75 mM KCl, 3 mM MgCl2, 10 mM DTT, 0.5 mM each dATP, dCTP, and dGTP, 0.2 mM dTTP, 0.05 mM Cy3-dUTP or Cy5-dUTP (Amersham), 40U RNAguard ribonuclease inhibitor (Amersham), and 400U Superscript II Rnase H- reverse transcriptase (Invitrogen). RT reactions were incubated at 42 degrees C for 2.5 h, followed by addition of 0.025U RNase A (Sigma) and 1.5U RNase H (New England BioLabs) and incubation at 37 degrees C for 30 min. Labeled targets were cleaned using the Qiaquick PCR purification kit (Qiagen) and precipitated, with 300 mM sodium acetate, 1 ul of 20 ug/ul glycogen (Invitrogen), and 2.5 volumes of 100% ethanol, at -20 degrees C overnight. Each labeled target was recovered by centrifugation (14,000 rpm, 4 degrees C, 1 h), washed in 70% ethanol, air-dried, and resuspended in 60 ul of hybridization buffer: 50% deionized formamide, 5X SSC, 0.1% SDS, 5 ul of 5 ug/ul oligo dT (5’T18[Q-N]3’), 5 ul of 2 ug/ul BSA (Pierce), and 2 ul of 10 ug/ul sonicated human placental DNA (Sigma). Targets were incubated at 96 degrees C for 3 min, and then at 65 degrees C until applied to microarrays. Microarrays were prepared for hybridization by washing 2 X 5 min in 0.1% SDS, washing 5 X 1 min in MilliQ H2O, immersing 3 min in 95 degrees C MilliQ H2O, and drying by centrifugation (2000 rpm, 5 min, in 50 ml conical tube). Microarray hybridizations were run in the dark under HybriSlips hybridization covers (Grace Biolabs) in slide hybridization chambers (Corning) submerged in a 45 degrees C water bath for 16 h. Coverslips were floated off in 45 degrees C (1X SSC, 0.2% SDS), and arrays were washed 1 X 10 min in 45 degrees C (1X SSC, 0.2% SDS), 3 X 4 min in room temperature (0.1X SSC, 0.1% SDS), and 4 X 4 min in room temperature 0.1X SSC. Slides were dried by centrifugation as before. Fluorescent images of hybridized arrays were acquired immediately at 10 um resolution using ScanArray Express (PerkinElmer). The Cy3 and Cy5 cyanine fluors were excited at 543 nm and 633 nm respectively, and the same laser power (90%) and photomultiplier tube (PMT) settings were used for all slides in a study (PMT 75 Cy3, PMT 63 or 64 Cy5 for head kidney study). Fluorescent intensity data were extracted from TIF images using Imagene 5.5 software (Biodiscovery). Keywords: other
2004-02-11 | GSE1031 | GEO
Project description:MicroPoly(A)Pure kits (Ambion) were used to prepare mRNA from P. salmonis-infected and control Atlantic salmon macrophages. Infected and control (24 h incubation) macrophage mRNA samples were subjected to two rounds of amplification using the MessageAmp aRNA kit (Ambion) and manufacturer's instructions. Approximately 400 ng of macrophage mRNA was used as template in the first round of amplification, yielding 8.1 ug of infected macrophage aRNA and 7.8 ug of control macrophage aRNA. Approximately 1 ug of first-round macrophage aRNA was used as template in the second round of amplification, yielding 81.2 ug of infected macrophage aRNA and 83.3 ug of control macrophage aRNA. Infected and control macrophage aRNA samples were visualized on agarose gels to check quality and quantity. Except for the amounts of aRNA and reverse transcription (RT) primer used, macrophage target labeling reactions and microarray hybridizations were identical. Macrophage target syntheses used 5 ug of second-round aRNA and 5 ug of random primers (Roche). RT primers were mixed with aRNA samples, and nuclease-free H2O (Invitrogen) was added to make 10 ul total volume. Samples were incubated at 70 degrees C 4 min, then placed on ice. RT reactions included 50 mM Tris HCl pH 8.3, 75 mM KCl, 3 mM MgCl2, 10 mM DTT, 0.5 mM each dATP, dCTP, and dGTP, 0.2 mM dTTP, 0.05 mM Cy3-dUTP or Cy5-dUTP (Amersham), 40U RNAguard ribonuclease inhibitor (Amersham), and 400U Superscript II Rnase H- reverse transcriptase (Invitrogen). RT reactions were incubated at 42 degrees C for 2.5 h, followed by addition of 0.025U RNase A (Sigma) and 1.5U RNase H (New England BioLabs) and incubation at 37 degrees C for 30 min. Labeled targets were cleaned using the Qiaquick PCR purification kit (Qiagen) and precipitated, with 300 mM sodium acetate, 1 ul of 20 ug/ul glycogen (Invitrogen), and 2.5 volumes of 100% ethanol, at -20 degrees C overnight. Each labeled target was recovered by centrifugation (14,000 rpm, 4 degrees C, 1 h), washed in 70% ethanol, air-dried, and resuspended in 60 ul of hybridization buffer: 50% deionized formamide, 5X SSC, 0.1% SDS, 5 ul of 5 ug/ul oligo dT (5'T18[Q-N]3'), 5 ul of 2 ug/ul BSA (Pierce), and 2 ul of 10 ug/ul sonicated human placental DNA (Sigma). Targets were incubated at 96 degrees C for 3 min, and then at 65 degrees C until applied to microarrays. Microarrays were prepared for hybridization by washing 2 X 5 min in 0.1% SDS, washing 5 X 1 min in MilliQ H2O, immersing 3 min in 95 degrees C MilliQ H2O, and drying by centrifugation (2000 rpm, 5 min, in 50 ml conical tube). Microarray hybridizations were run in the dark under HybriSlips hybridization covers (Grace Biolabs) in slide hybridization chambers (Corning) submerged in a 45 degrees C water bath for 16 h. Coverslips were floated off in 45 degrees C (1X SSC, 0.2% SDS), and arrays were washed 1 X 10 min in 45 degrees C (1X SSC, 0.2% SDS), 3 X 4 min in room temperature (0.1X SSC, 0.1% SDS), and 4 X 4 min in room temperature 0.1X SSC. Slides were dried by centrifugation as before. Fluorescent images of hybridized arrays were acquired immediately at 10 um resolution using ScanArray Express (PerkinElmer). The Cy3 and Cy5 cyanine fluors were excited at 543 nm and 633 nm respectively, and the same laser power (90%) and photomultiplier tube (PMT) settings were used for all slides in a study (PMT 72 Cy3, PMT 63 or 64 Cy5 for macrophage study). Fluorescent intensity data were extracted from TIF images using Imagene 5.5 software (Biodiscovery). Keywords: other
2004-02-11 | GSE1012 | 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:Erythrocytes were infected with Plasmodium chabaudi chabaudi AS strain expressing GFP. After 2 or 3 passages, a suspension of 100,000 infected erythrocytes in 1X-PBS (adjusted volume of 200µl) were injected i.p. in wild-type C57BL/6j mice and Homozygous mutant Ighm tm1Cgn mice (lacking mature B-cells). As a control, wild-type C57BL/6j mice and Homozygous mutant Ighm tm1Cgn mice were injected i.p with PBS. There were 3 mice (biological replicates) for each of the 4 experimental conditions. Parasitemia was monitored by flow cytometry and PCR weekly. 117 days post infection, mice were euthanized in CO2 chamber and femur and tibia bones were collected in 1X-HBSS/2% FBS. The cells were removed from the bones and the erythrocytes lysed by hypotonic lysis. Cells (20 million) were antibody stained and the 100K cells (Live/CD11b+/Ly6G-/F4/80+) were sorted in 1X-HBSS/20% FBS. For each sample. 50,000 viable cells were pelleted and lysed with cold ATAC-Resuspension Buffer (RSB) containing 0.1% NP40, 0.1% Tween-20, and 0.01% Digitonin and incubated in ice for 3 minutes. The lysaste was washed with 1 ml of cold ATAC-RSB containing 0.1% Tween-20 but NO NP40 or digitonin. Nuclei were pelleted at 500 RCF for 10 min at 4 degrees celcius. The supernatant was discarded and the pellet was resuspended in 50 uL of transposition mixture (25 ul 2x TD buffer, 2.5 ul transposase (100nM final), 16.5 ul PBS, 0.5 ul 1% digitonin, 0.5 ul 10% Tween-20, 5 ul H2O). The reaction was incubated for 30 minutes in a thermomixer with 1000 RPM mixing. Zymo DNA Clean and concentrator kit (cat# D4014) was used as a cleanup step. The DNA was amplified at 98 degrees C for 30 seconds, then 13 cycles of: 98 degrees C for 10 seconds, 63 degrees C for 30 seconds, 72 degrees C for 1 minute.The library was evaluated in an Agilent TapeStation system and the DNA concentration evaluated by Qubit. Sequencing was performed on Illumina Nextseq 500 with Buffer cartridge v2: Ref: 15057941, High output reagent cartridge v2: Ref: 15057934, NextSeq accessory Box v2: Ref: 15058251, and High output Flow Cell cartridge v2.5: Ref: 20022408
2022-01-12 | E-MTAB-10086 | biostudies-arrayexpress
Project description:Patients received standardized coartem therapy. Briefly, each pill contains 20 mg of artemether and 120 mg of lumefantrine. The dose and total coarse of tablets is based on the patients body weight. Blood was drawn from patients prior to anti-malarial treatment (day 0) and after treatment (day42 for children and day 28 for adults). Peripheral Blood Mononuclear Cells were isolated from all patients. Briefly, for PBMC isolation, whole blood from was diluted 1:2 in sterile PBS and overlaid on Ficoll Paque-PLUS in 50 mL conical tubes and centrifuged 800xg for 15 minutes at 25°C with no brake. Resulting buffy coats were collected and washed twice in RPMI 1640 medium, and then cells were treated with Red Blood Cell Lysis Buffer for 3 minutes at room temperature. Cells were washed in RPMI and counted on a hemacytometer. Monocytes were purified from PBMC using a miltenyi Pan Monocyte Isolation negative selection kit according to the manufacturer's instructions. For each sample. 50,000 viable cells were pelleted and lysed with cold ATAC-Resuspension Buffer (RSB) containing 0.1% NP40, 0.1% Tween-20, and 0.01% Digitonin and incubated in ice for 3 minutes. The lysaste was washed with 1 ml of cold ATAC-RSB containing 0.1% Tween-20 but NO NP40 or digitonin. Nuclei were pelleted at 500 RCF for 10 min at 4 degrees celcius. The supernatant was discarded and the pellet was resuspended in 50 uL of transposition mixture (25 ul 2x TD buffer, 2.5 ul transposase (100nM final), 16.5 ul PBS,0.5 ul 1% digitonin, 0.5 ul 10% Tween-20, 5 ul H2O). The reaction was incubated for 30 minutes in a thermomixer with 1000 RPM mixing. Zymo DNA Clean and concentrator kit (cat# D4014) was used as a cleanup step. The DNA was amplified at 98 degrees C for 30 seconds, then 13 cycles of: 98 degrees C for 10 seconds, 63 degrees C for 30 seconds, 72 degrees C for 1 minute.The library was evaluated in an Agilent TapeStation system and the DNA concentration evaluated by Qubit. Sequencing was performed on Illumina Nextseq 500 with Buffer cartridge v2: Ref: 15057941, High output reagent cartridge v2: Ref: 15057934, NextSeq accessory Box v2: Ref: 15058251, and High output Flow Cell cartridge v2.5: Ref: 20022408
2022-04-24 | E-MTAB-11643 | biostudies-arrayexpress
Project description:We used DNA microarrays to investigate the impact of indole and 7-hdroxyindole on P. aeruginosa PAO1.For the microarray experiments, 10 g glass wool (Corning Glass Works, Corning, N.Y.) were used to form biofilms in 250 mL in 1 L Erlenmeyer shake flasks which were inoculated with overnight cultures of P. aeruginosa PAO1 diluted that were 1:100. For P. aeruginosa with 7-hydroxyindole and indole, 500 uM 7-hydroxyindole in 250 uL DMF, 1000 uM indole in 250 uL DMF, or 250 uL DMF alone were added to cells grown in LB. The cells were shaken at 250 rpm and at 37oC for 7 h to form biofilms on the glass wool, and RNA was isolated from the biofilm cells. Keywords: comparison with E. coli signal indole on P. aeruginosa PAO1
2008-11-21 | GSE10065 | GEO
Project description:Sample preparation: P-AMPK+AMP, P-AMPK+ATPγS, and AMPK+ATPγS protein samples were crosslinked in HBST buffer (25 mM HEPES pH 7.5 at room temperature, 200 mM NaCL, and 1 mM TCEP). Non-crosslinked negative controls were generated using the same procedure without the addition of DSSO. Reactions were initiated by spiking 1 uL of 75 mM DSSO (Thermo-Fisher) in DMSO into a 50 uL solution containing 10 uM protein and mixing. The final molar ratio of crosslinker:protein was 150:1. The reactions were incubated at 25°C for 45 minutes prior to being quenched by the addition of Tris pH 8.0 to a final concentration of 50 mM. Each crosslink reaction was done in triplicate and the reaction replicates were pooled after quenching. 10 μL samples of the pooled samples were loaded for SDS-PAGE analysis with Coomassie staining to confirm the presence of crosslinked protein. The remaining 140 μL of crosslinked and non-crosslinked samples were then acetone precipitated at -20°C overnight and the protein was pelleted by centrifugation at 16,000 rcf for 5 minutes at 4°C. After decanting, the pellets were dried for 15 minutes at room temperature before being resuspended in 12.5 uL of resuspension buffer (50 mM ammonium bicarbonate, 8M urea, pH 8.0). ProteaseMAX (Promega) was added to 0.02% and the solutions were mixed on an orbital shaker operating at 400 RPM for 5 minutes. After resuspension, 87.5 uL of digestion buffer (50 mM ammonium bicarbonate, pH 8.0) was added. Cysteines in the protein samples were reduced and akylated as follows. DTT was added to 5 mM final concentration and the protein solutions were incubated at 56°C in an orbital shaker operating at 400 RPM and for 20 minutes. After reduction, 2.7 uL of 550 mM iodoacetamide was added and the solutions were incubated in the dark at room temperature for 15 minutes. Reduced and alkylated protein solutions were digested using trypsin at a ratio of 1:200 (w/w trypsin:protein) and incubating at 37°C. After overnight incubation at 37°C, the samples were acidified by the addition of trifluoroacetic acid (TFA, Thermo-Fischer) to 1%. Samples were then frozen and stored at -20°C until analysis.
2021-07-08 | PXD019017 | Pride
Project description:We used DNA microarrays to investigate the impact of indole and 7-hdroxyindole on P. aeruginosa PAO1.For the microarray experiments, 10 g glass wool (Corning Glass Works, Corning, N.Y.) were used to form biofilms in 250 mL in 1 L Erlenmeyer shake flasks which were inoculated with overnight cultures of P. aeruginosa PAO1 diluted that were 1:100. For P. aeruginosa with 7-hydroxyindole and indole, 500 uM 7-hydroxyindole in 250 uL DMF, 1000 uM indole in 250 uL DMF, or 250 uL DMF alone were added to cells grown in LB. The cells were shaken at 250 rpm and at 37oC for 7 h to form biofilms on the glass wool, and RNA was isolated from the biofilm cells. Keywords: comparison with E. coli signal indole on P. aeruginosa PAO1 For the microarray experiments, 10 g glass wool (Corning Glass Works, Corning, N.Y.) were used to form biofilms in 250 mL in 1 L Erlenmeyer shake flasks which were inoculated with overnight cultures of P. aeruginosa PAO1 diluted that were 1:100. For P. aeruginosa with 7-hydroxyindole and indole, 500 uM 7-hydroxyindole in 250 uL DMF, 1000 uM indole in 250 uL DMF, or 250 uL DMF alone were added to cells grown in LB. The cells were shaken at 250 rpm and at 37oC for 7 h to form biofilms on the glass wool, and RNA was isolated from the biofilm cells.
2010-10-23 | E-GEOD-10065 | biostudies-arrayexpress
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: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