Mass spectrometric sequencing of linear peptides by product-ion analysis in a reflectron time-of-flight mass spectrometer using matrix-assisted laser desorption ionization

Authors

  • R. Kaufmann,

    1. Institute of Laser Medicine, Heinrich-Heine-University, PO Box 101007, D-40001 Düsseldorf, Germany
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  • B. Spengler,

    Corresponding author
    1. Institute of Laser Medicine, Heinrich-Heine-University, PO Box 101007, D-40001 Düsseldorf, Germany
    • Institute of Laser Medicine, Heinrich-Heine-University, PO Box 101007, D-40001 Düsseldorf, Germany
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  • F. Lützenkirchen

    1. Institute of Laser Medicine, Heinrich-Heine-University, PO Box 101007, D-40001 Düsseldorf, Germany
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Abstract

In matrix-assisted laser desorption ionization (MALDI) a large fraction of analyte ions undergo post-source decay (PSD) during flight in the field-free drift path. By means of a modified two-stage reflectron, product ion time-of-flight spectra of medium-sized linear peptides (up to 2800 u) were recorded, containing full sequence information. Precision, accuracy and mass resolution of fragment ions were almost as good as obtained in high-energy collisionally activated dissociation (CAD) studies performed in four-sector instruments. Instrumental sensitivity was better by at least one order of magnitude. In reflectron time-of-flight mass spectrometry (RETOF-MS) the cleavage pattern of PSD products is different from that obtained by high-energy and low-energy CAD. Activation mechanisms of PSD were found to be largely determined by collisional events (ion/neutral) occurring in the acceleration field during early plume expansion. Future potentials of PSD analysis after MALDI are discussed.

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