Thermo Finnigan LLC

Roza I Viner

Michael A Blank

Vladimir Zabrouskov

Torsten Ueckert

Qiang Zhang

A method of generating an inclusion list for targeted mass spectrometric analysis is disclosed. Experimentally-acquired data for a plurality of isobarically-labeled peptides derived by proteolytic digestion of a corresponding protein. The data includes, for each of the isobarically-labeled peptides, a mass-to-charge (m/z) ratio, a charge state, and a chromatographic retention time (RT). The method includes determining a hydrophobicity index (HI) of an unlabeled peptide corresponding to the isobarically-labeled peptide. If the determined HI is less than a threshold value, a substitute unlabeled peptide is selected in accordance with predetermined criteria and predicted properties for the substitute peptide are determined and stored on an inclusion list. If the determined HI for the unlabeled peptide is at least as great as the threshold value, predicted properties for the unlabeled peptide are determined and stored on an inclusion list. The substitute unlabeled peptide may be selected from an available peptide library.

Method of generating an inclusion list for targeted mass spectrometric analysis

A method of generating an inclusion list for targeted mass spectrometric analysis is disclosed. Experimentally-acquired data for a plurality of isobarically-labeled peptides of interest is received at a computer. The data includes, for each of the isobarically-labeled peptides, a mass-to-charge (m/z) ratio, a charge state, and a chromatographic retention time. Predicted properties for a corresponding unlabeled peptide are determined via the computer. The predicted properties include a predicted m/z, a predicted charge state, and a predicted chromatographic retention time. The predicted properties for each corresponding unlabeled peptide are stored to the inclusion list. The predicted chromatographic retention time for the corresponding unlabeled peptide is determined based on hydrophobicity indices of the isobarically-labeled peptide and the corresponding unlabeled peptide, and chromatographic conditions for the targeted mass spectrometric analysis.

The present invention is directed to methods of merging spectral data resulting from collision fragmentation processes, such as, for example, Pulsed Q Dissociation (PQD), high-energy collision-induced dissociation (HCD), electron transfer disassociation (ETD), collision-induced dissociation (CID), and photo-dissociation processes, such as, but not limited to, infrared multi-photon photo-dissociation (IRMPD), to provide the desired qualitative and quantitative information on a single peptide. By merging such ETD, CID, or IRMPD scans with corresponding HCD scans that are obtained on the same precursor, the quality of the resulting spectrum is increased so as to provide more confident identification of peptides and correspondingly the quantification is enhanced because the HCD method of the MS/MS spectrum produces higher abundances of detectable reporter ions. Such methods, as disclosed herein, are especially applicable for peptides which experience predominant neutral loss in the ion trap, e.g., phosphorylated.

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Fremont, CA, United States of America

Roza I Viner