Comparison of Peptide Fragmentation With Different Ionization Techniques: Variation With Sample Preparation Method of the Fragmentation of Luteinizing Hormone-Releasing Hormone Following Plasma Desorption

Abstract

The fragmentation patterns of the peptide luteinizing hormone-releasing hormone (LH-RH) measured in plasma desorption mass spectrometry (PDMS) and keV-atom bombardment have been compared with the field desorption (FD) mass spectrum. Several different methods of preparing the samples for PDMS have been investigated, including application to a nitrocellulose surface which was preadsorbed with a protein. Similar fragment ions were observed in keV-atom bombardment and in PDMS applied to nitrocellulose which had not been preadsorbed with a protein; different fragment ions have been observed in FD mass spectrometry. The PDMS fragmentation when LH-RH was applied to nitrocellulose which had been preadsorbed with thioredoxin was found to differ yet again. The differences in the fragmentation are rationalized on the basis of differences in conformational constraints.