Use of Ionspray Mass Spectrometry in the Speciation and Elemental Characterization of Metallothioneins

Abstract

Results are presented to illustrate the potential and limitations of ionspray mass spectrometry in the characterization of metal containing proteins, metallothioneins (MTs). Through collision induced dissociation in the interface sampling region of a mass spectrometer, ionspray can be used to obtain species and elemental information on small molecules. When larger ions, such as MTs, are analyzed after chromatographic separation, similar information can only be obtained indirectly. Post-column acidification of the solution was used to release protein bound metal ions into solution prior to their determination by ionspray mass spectrometry. This approach allows MT species and metal ions freed from MTs to be determined using a single experimental set-up. Extensive on-column metal displacement was observed under the chromatographic conditions used.