Figure 1

MS-based approach diagrammatic representation. (A) Once a protein is digested, the theoretically possible disulfide bonded peptides are compared with experimentally obtained precursor ions. In order to confirm each correspondence, the possible disulfide bonded fragment ions are next compared with experimentally generated MS/MS spectra. (B) Most of the different fragment ions (and their nomenclature) that can be observed. Ions types not represented here include b and y ions which have either lost a water molecule (b^o, y^o) or have lost an ammonia molecule (b^*, y^*).