Fast on-column protein digestion with subsequent peptide mapping using tandem mass spectrometry with information dependent acquisition

A platform for rapid on-line protein digestion of protein mixtures for direct infusion to a mass spectrometer is presented. A mixture of protein A, staphylococcal enterotoxin B and cytochrome c was used as a model mixture injected on a gel filtration column and a trypsin reactor which were connected in series to a micro liquid chromatography (μLC) system. The peptides in the column eluate were analyzed with ESI tandem mass spectrometry, utilizing information dependent acquisition (IDA). In one step, the proteins in the mixture (μM concentrations) were concomitantly desalted, separated, digested and identified with an overall analysis time of less than 40 min. Protein sequence coverage of 78-95% for the involved substances was achieved.