Enhanced gas-phase hydrogen-deuterium exchange of origonucleotide and protein ions stored in an external multipole ion reservoir

Rapid gas-phase hydrogen-deuterium (B-D) exchange from D2O and ND3 into oli gonucleotide and protein ions was achieved during storage in a hexapole ion reservoir, Deuterated gas is introduced through a capillary line that disc harges directly into the low-pressure region of the reservoir, Following ex change, the degree of A-D exchange is determined using Fourier transform io n cyclotron resonance mass spectrometry, Gas-phase H-D exchange experiments can be conducted more than 100 times faster than observed using convention al in-cell exchange protocols that require lower gas pressures and addition al pump-down periods. The short experimental times facilitate the quantitat ion of the number of Labile hydrogens for less reactive proteins and struct ured oligonucleotides. For ubiquitin, we observe similar to 65 H-D exchange s after 20 s, Exchange rates of >250 hydrogens s(-1) are observed for oligo nucleotide ions when D2O or ND3 is admitted directly into the external ion reservoir owing to the high local pressure in the hexapole, Partially deute rated oligonucleotide ions have been fragmented in the reservoir using infr ared multiphoton dissociation (IRMPD), The resulting fragment ions show tha t exchange predominates at charged sites on the 5'- and 3'-ends of the olig onucleotide, whereas exchange is slower in the core, This hardware configur ation is independent of the mass detector and should be compatible with oth er mass spectrometric platforms including quadrupole ion trap and time-of-f light mass spectrometers. Copyright (C) 2000 John Wiley & Sons, Ltd.