Gas-phase conformers of the [M+2H](2+) ion of bradykinin investigated by combining high-field asymmetric waveform ion mobility spectrometry, hydrogen/deuterium exchange, and energy-loss measurements

The continuous separation capability of high-field asymmetric waveform ion mobility spectrometry (FAIMS) was used in combination with complementary te chniques for probing biomolecular ions in the gas phase. Gas-phase conforme rs of the [M + 2H](2+) ion of bradykinin were examined using a combination of FAIMS, H/D exchange, and energy-loss measurements. When FAIMS data and H /D exchange data were analyzed separately, the presence of only two conform ers of the [M + 2H](2+) ion of bradykinin could be detected. However, in an experiment in which FAIMS and H/D exchange were combined, at least four di fferent conformers of the gas-phase [M + 2H](2+) ion of bradykinin were det ected, including one of very low abundance. Cross sections calculated for t he four conformers, based on energy-loss measurements, were 250, 240, 250, and 244 Angstrom (2), in order of decreasing abundance. Copyright (C) 2001 John Wiley & Sons, Ltd.