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 The CNRU Mass Spectrometry Core Facility is equipped for advanced Difference In Gel Electrophoresis (DIGE) experiments.
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MALDI MS AND AP-MALDI MS/MSMatrix-Assisted Laser Desorption Ionization (MALDI) is a method used to generate gas phase ions from peptide mixtures. Sample (typically desalted using a C18 clean up tip) is mixed with a UV-absorbing matrix (usually α-Cyano-4-hydroxycinnamic acid). About 1 ul of this mixture is spotted onto a sample plate and allowed to dry. The sample co-crystallizes with the matrix. The plate is then inserted into the source region of the mass spectrometer and a laser with a UV wavelength (generally nitrogen at 337 nm) fires a beam of photons at the sample. The matrix absorbs the photon energy and explodes off the plate, bringing the sample with it. Collisions in the plume above the plate lead to declustering and ionization of the peptides. The gas phase ions are then extracted with a voltage and directed into the mass spectrometer.At the CNRU Mass Spectrometry Core Facility, we have an Atmospheric MALDI (AP-MALDI) source interfaced to our Agilent ion trap. This allows us to obtain singly-charged peptide ions that we can then fragment. We also have a Bruker MALDI-TOF for peptide mass mapping applications.  MS spectrum of an in gel digest from a spot excised from a 2D gel separation of E. coli proteins obtained using AP-MALDI on the ion trap. This data was searched using MASCOT and an identification of periplasmic oligopeptide binding protein was obtained with a significant score of 59. The ion at m/z 1636.9 was selected for fragmentation.  MS spectrum of the ion at m/z 1636.9. The product ion spectrum was searched using MASCOT and an identification of periplasmic oligopeptide binding protein was obtained, verifying the identification obtained using mass mapping. |
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