SURFACE-INDUCED DISSOCIATION - AN EFFECTIVE TOOL TO PROBE STRUCTURE, ENERGETICS AND FRAGMENTATION MECHANISMS OF PROTONATED PEPTIDES

The utility of surface-induced dissociation (SID) to probe the structu re, energetics and fragmentation mechanisms of protonated peptides is discussed and demonstrated, High internal energy deposition provided b y low-energy (eV range) ion-surface collisions yields extensive fragme ntation of protonated peptides, allowing relatively uncomplicated and rapid sequence analysis of oligopeptides. SID of multiply protonated p eptides is illustrated for peptides with molecular mass of up to simil ar to 5000 u. It is also illustrated that SID combined with electrospr ay ionization (ESI) provides a distinctive experimental technique to d etermine the energetics and mechanisms of peptide fragmentation. The r elative position of ESI/SID fragmentation efficiency curves (plots of percentage fragmentation vs, laboratory collision energy) for peptides can be utilized to estimate relative energetics of peptide fragmentat ion and even to predict proton localization sites. The observed trends support the essential role of the mobile proton model in understandin g peptide fragmentation by low-energy tandem mass spectrometry.