Fig. 2.

(A) Electrospray mass spectrum of the combined fractions of bovine αB-crystallin from size-exclusion chromatography. Signal is observed between 7,000 and 15,000 m/z, with the most intense peaks at ≈10,000 m/z. These peaks are not due to a charge-state series of a single oligomer but rather to the overlap of several such series from different-sized oligomers. The spectrum was acquired at a voltage applied to the collision cell of 4 V. (B) Mass spectra obtained for a range of collision energies demonstrate that αB-crystallin oligomers undergo multiple loss of monomers, from one at a voltage applied to the collision cell of 120 V up to three at 200 V. (C) Expansion of the monomer region at voltages applied to the collision cell of 120, 160, and 200 V. The average charge state of the dissociated monomers was observed to decrease from 18+ at 120 V to 16+ at 160 V and 15+ at 200V.