Merging HCD and In-Trap CID Spectra for Peptide Identification
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Solution Overview
Problem
Current tandem mass spectrometry techniques face challenges in simultaneously achieving high-quality peptide identification and quantification due to low mass accuracy and resolution in MS/MS spectra, with methods like HCD compromising sequence ion intensity and in-trap CID compromising low-mass reporter ion abundance.
Innovation Solution
A method involving the merging of high-energy collision-induced dissociation (HCD) and in-trap induced MS/MS spectra to enhance peptide identification and quantification, utilizing hybrid mass spectrometers like the LTQ Orbitrap, and employing data processing techniques to combine and normalize spectra for improved database searches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-energy collision-induced dissociation (HCD) is used for MS/MS fragmentation, then reporter ion abundance is improved for quantification, but sequence ion intensity is compromised affecting peptide identification
Solution Approach 1:
The patent merges MS/MS spectra from two different fragmentation methods (HCD and in-trap CID) into a single composite spectrum. The HCD spectrum provides strong reporter ions for quantification, while the in-trap CID spectrum provides strong sequence ions for identification. By combining these complementary spectra, the method achieves both high quantification accuracy and reliable peptide identification simultaneously.
2Loss of information
If in-trap collision-induced dissociation (CID) is used for MS/MS fragmentation, then sequence ion intensity is improved for peptide identification, but low-mass reporter ion abundance is compromised affecting quantification
Solution Approach 1:
The patent combines MS/MS spectra from in-trap CID and HCD methods. The in-trap CID spectrum contributes strong sequence ions that improve peptide identification confidence, while the HCD spectrum contributes abundant reporter ions that enhance quantification accuracy. The merging process integrates these complementary information sources into a unified spectrum.
3Adaptability or versatility
If MS/MS spectra are used for peptide identification and quantification, then protein analysis capability is improved, but mass accuracy and resolution are reduced compromising spectral quality
Solution Approach 1:
The patent merges full-resolution MS spectra with MS/MS fragmentation spectra. The full-resolution spectrum provides accurate precursor ion masses, while the merged MS/MS spectrum incorporates both sequence ion and reporter ion information. This approach maintains high mass accuracy for peptide identification while enabling simultaneous quantification through reporter ion analysis.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach results in increased spectrum quality for confident peptide identification and enhanced quantification, particularly benefiting applications like in-vitro and proteomics analysis by increasing detectable reporter ions and improving quantitative statistics.
Implementation Method 1
Such a method often uses collision-induced dissociation (CID), wherein a mass-selected ion is transmitted to a high-pressure region so as to be subjected to low energy collisions with introduced inert gas molecules. Thereafter, as a molecular ion collides, a portion of its kinetic energy is converted into excess internal energy so as to render the ion unstable, which results in unimolecular fragmentation reactions
Implementation Method 2
Such techniques include a high-energy collision-induced dissociation (HCD) method, in which the precursor ions are accelerated to high velocities into a gas-filled collision cell
Implementation Method 3
a low-energy collision-induced dissociation (in-trap CID) method as similarly discussed above, in which the precursor ions are resonantly excited within the ion trap and undergo collisions with atoms or molecules of a damping gas
Data Source
AI summary
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.