Abstract: A method and system is provided for mass spectrometry for identification of a specific elemental formula for an unknown compound which includes but is not limited to a metabolite. The method includes calculating a natural abundance probability (NAP) of a given isotopologue for isotopes of non-labelling elements of an unknown compound. Molecular fragments for a subset of isotopes identified using the NAP are created and sorted into a requisite cache data structure to be subsequently searched. Peaks from raw spectrum data from mass spectrometry for an unknown compound. Sample-specific peaks of the unknown compound from various spectral artifacts in ultra-high resolution Fourier transform mass spectra are separated. A set of possible isotope-resolved molecular formula (IMF) are created by iteratively searching the molecular fragment caches and combining with additional isotopes and then statistically filtering the results based on NAP and mass-to-charge (m/2) matching probabilities.

Abstract: A method and system is provided for mass spectrometry for identification of a specific elemental formula for an unknown compound which includes but is not limited to a metabolite. The method includes calculating a natural abundance probability (NAP) of a given isotopologue for isotopes of non-labelling elements of an unknown compound. Molecular fragments for a subset of isotopes identified using the NAP are created and sorted into a requisite cache data structure to be subsequently searched. Peaks from raw spectrum data from mass spectrometry for an unknown compound. Sample-specific peaks of the unknown compound from various spectral artifacts in ultra-high resolution Fourier transform mass spectra are separated. A set of possible isotope-resolved molecular formula (IMF) are created by iteratively searching the molecular fragment caches and combining with additional isotopes and then statistically filtering the results based on NAP and mass-to-charge (m/2) matching probabilities.

Abstract: Disclosed is a method of determining two-dimensional nuclear- or rotating frame-Overhauser effect spectroscopy intensities for a ligand-enzyme system having flexible active cites, wherein the ligand-enzyme system has at least 3 conformational states. The first step is inputing data into a modeling computer of coordinates for each molecule on the enzyme and ligand, kinetic data, correlation times, and concentrations of ligand and enzyme. Next, a K matrix is created from the kinetic data, and an an R matrix is derived from the correlation times and the coordinates. A dynamic matrix D is created by summing the K and R matrices. This D matrix is symmetrized and diagonalized. Spectroscopy intensities are then derived from the symmetrized and diagonalized D matrix.