Average Activation Energies of Low-energy Fragmentation Processes of Protonated Peptides Determined by a New Approach

✍ Scribed by Károly Vékey; Árpád Somogyi; Vicki H. Wysocki

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 1021 KB
• Volume: 10
• Category: Article
• ISSN: 0951-4198
• DOI: 10.1002/(sici)1097-0231(19960610)10:8<911::aid-rcm593>3.0.co;2-7

✦ Synopsis

An attempt was made to estimate the average activation energies of low-energy fragmentation proceses of protonated oiigopeptides by combining RRKM theory and the results of electmspray ionization/surface induced dissociation (ESUSID). The average internal energy was assumed to be deposited by three processes: thermal energy gain& in the heated capillary of the electraspray source, energy gain in the capillary-skimmer region of the electrospray source, and energy deposition by collision with the surface. The latter fraction was calculated based on the position of the ESYSID fragmentation of efficiency curves and the ratio of kinetic to internal energy conversion in SID. Using the average internal energy estimated from the experimental results, the average activation energies were evaluated by applying RRKM theory. The application of thii approach for protonated leucine enkephalin resulted in an average activation energy of 3 6 i 5 k d m o l for the lowest energy decompositions. The approach has also been applied to severaI other peptides in the mass range of 2oelu)o Da, yielding average activation energies in the range of 35-47 kcal/mol.