| The Characteristics of In-source Decay in Mass Spectrometric Degradation Methods: Hydrogen-Attachment Dissociation (HAD) |
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* Graduate School of Integrated Science, Yokohama City University (22-2 Seto, Kanazawa-ku, Yokohama 236-0027, Japan) |
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| In-source decay (ISD) combined with matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometer (TOF MS) has been described by comparing with conventional mass spectrometric degradation (MSD) methods such as collision-induced dissociation (CID) and post-source decay (PSD). The ISD characteristic is the formation of c- and (z+2)-ions originated from the N-Cα bond cleavage on the peptide backbone, while the CID and PSD processes are the CO-NH bond cleavage which brings about b- and y-ion. Furthermore, the ISD processes occurring with 337 nm laser photon irradiation for peptide or protein proceed resulting in the formation of hyper-valent radical species via intermolecular hydrogen transfer between matrix and analyte molecules following the non-ergodic N-Cα bond cleavage. The non-ergodic N-Cα bond cleavage occurs in the MALDI ion source within nanosecond order, as an α-cleavage initiated with radical site at the carbonyl carbon. The MALDI-ISD method has been applied to three peptides and five proteins. | ||
| Key words: MALDI, In-source decay, Mass spectrometric degradation, Hydrogen-attachment dissociation | ||
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