Back to results
US 2025/0258181 A1Published application
Top Down Protein Identification Method
OwnerTakashi Babainventor
Life of this patent
Estimating the term…
Abstract
Systems and methods described herein can provide for “top down” mass spectrometric analysis of proteins or peptides in a sample using ExD, in some aspects via direct infusion of the sample to the ion source without on-line LC separation, while deconvoluting the ambiguity in the ExD spectra generated by impure samples. For example, methods and systems in accordance with various aspects of the present teachings can utilize patterns in charge-reduced species following ExD to correlate the ExD fragments with their precursor ions in order to more confidently identify the precursor ion from which the detected product ions originated.
Claims21
A method of processing a sample, comprising:
- utilizing an ion source to generate a plurality of precursor peptide or protein ions from a sample solution containing at least one peptide or protein;
- performing a survey of the plurality of precursor peptide or protein ions from the sample solution across a broad mass range, without subjecting the plurality of precursor ions to an ExD reaction, to generate a survey spectrum with a plurality of peaks corresponding to the respective ones of the plurality of precursor ions;
- applying bandpass filtering across the broad mass range of the precursor ions using a plurality of m/z isolation windows, representing narrow sub-ranges of interest from the broad mass range, determined based on the survey spectrum;
- subjecting the precursor ions within each of the m/z isolation windows to an ExD reaction;
- detecting product ions resulting from each of the ExD reactions so as to generate a plurality of ExD spectra corresponding to each of the m/z isolation windows, wherein at least a first ExD spectra corresponding to a first m/z isolation window exhibits one or more ExD fragment ions and one or more charge reduced species of the precursor ions within the first m/z isolation window;
- determining a precursor charge state and a molecular weight for one or more species of the precursor ions within the first m/z isolation window at least partially based on a m/z of the said one or more species of precursor ions within the first m/z isolation window and a m/z of the one or more charge reduced species of the precursor ions;
- and
- determining relationships between the ExD spectra corresponding to each of the plurality of m/z isolation windows to identify patterns existing in the presence of fragment ions resulting from precursor ions having the same charge state and similar molecular weight.
5 more elements
A mass spectrometer system, comprising:
- an ion source configured to generate a plurality of precursor peptide or protein ions from a sample solution containing at least one peptide or protein;
- a mass analyzer configured to receive the plurality of precursor ions from the ion source;
- an ExD reaction cell configured to receive the precursor ions transmitted from the mass analyzer and subject the precursor ions to an ExD reaction;
- a detector;
- and
- a controller, wherein the controller is configured to:
- perform a survey of the plurality of precursor peptide or protein ions from the sample solution across a broad mass range, without subjecting the plurality of precursor ions to an ExD reaction, to generate a survey spectrum with a plurality of peaks corresponding to the respective ones of the plurality of precursor ions;
- apply bandpass filtering across the broad mass range of the precursor ions using a plurality of m/z isolation windows, representing narrow sub-ranges of interest from the broad mass range, determined based on the survey spectrum, and subject the precursor ions within each of the m/z isolation windows to an ExD reaction within the ExD reaction cell;
- generate a plurality of ExD spectra of product ions resulting from the ExD reactions corresponding to each of the m/z isolation windows, wherein at least a first ExD spectra corresponding to a first m/z isolation window exhibits one or more ExD fragment ions and one or more charge reduced species of the precursor ions within the first m/z isolation window;
- determine a precursor charge state and a molecular weight for one or more species of the precursor ions within the first m/z isolation window at least partially based on a m/z of the said one or more species of precursor ions within the first m/z isolation window and a m/z of the one or more charge reduced species of the precursor ions;
- and
- determine relationships between the ExD spectra corresponding to each of the plurality of m/z isolation windows to identify patterns existing in the presence of fragment ions resulting from precursor ions having the same charge state and similar molecular weight.
9 more elements
Dependencies are inferred from the claim text.