US 2008/0300795 A1 · Evaluating the probability that MS/MS spectral data matches candidate sequence data

Abstract

In one aspect of the present invention a new database search methodology is provided that provides a probability that spectral data from a non-ergodic reaction via mass spectrometry matches a candidate sequence from a set of sequences in a database by random. The methodology comprises two parts. The first part pre-processes the spectral data and retains only the most relevant data for the database search. The second part comprises searching a database using the pre-processed spectrum to assign a probability or expectation that the spectrum matches a candidate sequence from a set of sequences in a database by random. The search methodology uses a new probability model, a compound distribution based on the number of product ion mass-to-charge ratios and the number of intensity values that are shared between the product ion spectral data and the sequence database, to accurately predict the probability of the peptide identification being a correct match, and not a random event.

Claims20

Dependent claims

A method for generating a compound probability that product ion spectral data matches a candidate sequence in a sequence database by random, the product ion spectral data having been generated by a non-ergodic process, and the method comprising the steps of:

(a) acquiring first product ion spectral data;
(b) preprocessing the first product ion spectral data;
(c) determining product ion abundance values and product ion mass-to-charge ratio values for each of a plurality of peaks from the pre-processed first product ion spectral data;
(d) utilizing the product ion abundance values to determine an intensity probability distribution, the intensity probability distribution representing a first probability that the product ion spectral data was generated at random;
(e) utilizing the mass-to-charge ratio values of the product ions to determine a fragment probability distribution, the fragment probability distribution representing a second probability that the product ion spectral data was generated at random;
and
(f) determining the compound probability based on the intensity probability distribution and the fragment probability distribution, the probability representing a probability that the generated product ion spectral data matches a candidate sequence in the sequence database at random.

4 more elements

Dependencies are inferred from the claim text.

Evaluating the probability that MS/MS spectral data matches candidate sequence data

Life of this patent

Evaluating the probability that MS/MS spectral data matches candidate sequence data

Life of this patent

Abstract

Claims20