Gas-phase concentration, purification, and identification of whole proteins from complex mixtures

Abstract

Five proteins present in a relatively complex mixture derived from a whole cell lysate fraction of E. coli have been concentrated, purified, and dissociated in the gas phase, using a quadrupole ion trap mass spectrometer. Concentration of intact protein ions was effected using gas-phase ion/ion protontransfer reactions in conjunction with mass-to-charge dependent ion "parking" to accumulate protein ions initially dispersed over a range of charge states into a single lower charge state. Sequential ion isolation events interspersed with additional ion parking ion/ion reaction periods were used to "charge-state purify" the protein ion of interest. Five of the most abundant protein components pr..