#04011: Photodissociation of peptide ions using vacuum ultraviolet light
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TECH FIELD(S)
Proteomics
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FEATURES
Peptide ions in a tandem time of flight (TOF-TOF) mass spectrometer are fragmented by irradiation with 157 nm light from an excimer laser, producing non-specific but easily interpreted fragmentation spectra with excellent sequence coverage. For peptides containing a single highly basic residue, the charge is retained on the fragment containing the basic group. This can result in mainly one type of ion fragment for peptides with a terminal basic group, such as those produced by the tryptic digestion of a protein.
The unusual features observed when peptide ion fragmentation is induced by 157 nm light indicate that fragmentation is generated by a direct photochemical process, and that the chromophore involved must be present along the peptide backbone. This reaction results in homolytic radical cleavage, a process that appears to bypass any of the energy relaxation process commonly involved in other fragmentation processes. Because this bond cleaves before the energy is redistributed, the resulting fragmentation pattern differs significantly from the sequence dependent statistical distribution obtained when the analyte is vibrationally excited.
Most other fragmentation processes are charge-induced, so charge localization by basic groups in a peptide has not been possible. This charge localization ensures that for certain analytes, one fragment series will be dominant.
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BENEFITS
The ability to generate de novo sequences from peptides rapidly, reliably and with high sensitivity. This will increase the reliability of peptide identifications, and will also make it much easier to identify peptides that do not match exactly to a database, due to modification, database errors or mutations. Moreover, this method of ion fragmentation is compatible with nearly all, if not all, types of commercial ion source and mass spectrometer.
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INVENTOR(S)
James P. Reilly and Matthew S. Thompson
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INTELLECTUAL PROPERTY STATUS
US Patent Pending
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CONTACT INFORMATION
For additional information on this technology, please contact Bill Brizzard, Director of Technology Transfer , IURTC:
Indiana University Research & Technology Corporation
501 North Morton Street, Suite 204
Bloomington, IN 47404
Telephone:812-855-3597
bbrizzar@iu.edu
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