ICP-MS-assisted identification of selenium-containing proteins in 2D gels using a new capillary HPLC–ICP MS interface and Orbitrap tandem mass spectrometry

An improved instrumental approach is discussed for the identification of Se-containing proteins separated by 2D polyacrylamide gel electrophoresis. A protein, detected in a gel by laser ablation ICP-MS 2D 78Se imaging, was excised from another gel obtained in parallel under identical conditions, and digested with trypsin. Selenium-peptides were detected by capillary HPLC–ICP MS using a new robust commercial interface and an ICP mass spectrometer fitted with a frequency-matching RF generator facilitating work at high concentrations of acetonitrile in the mobile phase. The identification of selenopeptides was carried out by means of hybrid linear quadrupole trap-Orbital trap MS offering a higher intrascan dynamic range and better mass accuracy than the hitherto used Q-TOF (time-of-flight) mass spectrometers. An example of the identification of Se-containing glyceraldehyde-3-phosphate dehydrogenase-3 in yeast is discussed.