|
Keck
Home Page >
Protein Chemistry >
Mass Spectrometry: MALDI
Mass Spectrometry:
Matrix Assisted
Laser Desorption Ionization
MALDI (Matrix Assisted Laser
Desorption Ionization) MS in positive ionization mode is used to obtain
intact protein masses, for comparative tryptic peptide mapping,
screening of RP-HPLC isolated tryptic peptides prior to Edman
sequencing, peptide biomarker discovery, and Q/C of peptides made in
the Keck Peptide Synthesis Resources. Masses can be obtained on 1-500
fmol of 750-2,500 Da peptides with an average mass accuracy (external
calibration) of <150 ppm (parts per million) in linear and 70 ppm in
reflectron mode – which provides monoisotopic peptide masses. A variety
of biomolecules can be analyzed including oligosaccharides,
gangliosides, and proteins that are up to ~250,000 Da. Because of
matrix interference, the lower mass limit is about 750 Da. Protein
solutions in 10 μM volatile buffers can be analyzed directly while
samples with higher salt concentrations require prior C4 ZipTip
desalting.
|
