Protein Identification
Electrospray Mass Spectrometry
- Thermo Electron DECA XP+ Mass Spectrometer
- Protein/peptide identification from enzymatic digest
- Identifiction of protein modifications
- $30.00 per run
- Please contact the facility if you are interested in this service at (806) 742-3722 X 226
- Instrument details listed below
- Electrospray Mass Spectrometry Order Form
MALDI-TOF/TOF Mass Spectrometry
- ABI/MDS SCIEX 4800 Mass Spectrometer
- Analysis of peptides, proteins and other small molecules
- Identification of proteins and analysis of post-translational modifications
- Determination of molecular weight of intact proteins
- $20.00 per run
- Please contact the facility if you are interested in this service at (806) 742-3722 X 226
- Instrument details listed below
- MALDI-TOF/TOF Mass Spectrometry Order Form
DECA XP+ Mass Spectrometer Instrument Details
The facility has a Thermo Electron DECA XP+ electrospray ionization mass spectrometer (ESI MS) in line with a Surveyer liquid chromatography (LC) system and autosampler. The instrument is used for protein/peptide identification from an enzymatic digest on less than 1 pmol of sample. A protocol of in-gel tryptic digest of a protein band is available on our website.
Briefly, a peptide digest is injected via HPLC onto a capillary column for nanospray ionization. The peptides of the digest are separated on the reverse phase column, plus ionized to individual ion droplets at the tip of the column. The peptide ions at the acidic PH of the mobile phase are positively charged and are introduced into the ion trap in positive ion mode by adjusting voltage. A vacuum allows the ions to move unimpeded. Ions are "trapped" with a combination of voltage frequency adjustments and then ions o f aspecific mass-to-charge ratio (m/z) are allowed to scan out and be detected as (MS) data or remain "trapped". Trapped ions can be further subjected to collisions with gas molecules and a change in radio frequency to produce "collision-induced" dissociation of the trapped peptide ions. The fragments produced ("product ions") can then be ejected from the trap to produce the MS/MS spectrum.
The MS and MS/MS data can then be used to search databases for identification and often detect the exact sequence location of modificatons on the peptide (eg: phosphorylation sites and researcher-induced modifications).
MALDI-TOF/TOF Mass Spectrometer Instrument Details
The facility houses a MALDI-TOF/TOF 4800 (ABI/SCIEX) mass spectrometer used for analysis of peptides, proteins and other molecules. This instrument is able to identify proteins at sub-fmole levels with a high mass accuracy (less than 50 ppm). In order to perform the measurement, the digested protein (eigher in-gel or in-solution) will be mixed with a matri solution (CCA is most commonly used for peptide analyses) and 0.5μl of the following mixture will be spotted to a MALDI target plate. The expeiment can be performed in MS mode (TOF) with selected peptides undergoing a further MS/MS (TOF/TOF) mode to predict the sequence of the peptides. The combination of data obtained from MS and MS/MS can increase significantly the confidence of protein identification using a database search (MASCOT). The instrument can also be used for molecular weight determination of intact proteins.
The analysis of post-translational modifications (PTMs) in proteins is another important task in proteomics. MALDI-TOF/TOF is well suited to be used for the analysis of PTMs such as phosphorylation, acylation, etc. We support a license for our database search engine, MASCOT, so that we will be able to introduce any specific sort of modification upon request.
Please direct all inquiries about the use of this instrument for your research to the Center staff. Other peripheral services are also available, such as proteolytic digestion (typically trypsin), zip-tip desalting/purification, consultation on quantitation methods, 2D-gel electrophoresis and column chromatographic protein pruification/separation technologies.