Patent ID: 8129335

Claim:
A method of determining the molecular flux rates of a plurality of proteins in a cell, tissue or organism, said method comprising: a) administering one or more isotope-labeled protein precursors selected from the group consisting of 2 H 2 O, H 2 18 O, 13 CO 2 , C 18 O 17 O, H 16 CO 3 , 15 NH 3 , and 15 N-labeled amino acids to said cell, tissue or organism for a period of time sufficient for the 2 H 2 O to be incorporated into proteins in the cell, tissue or organism; b) obtaining a sample from the cell, tissue, or organism, wherein the sample comprises a plurality of proteins; c) degrading the plurality of proteins to form a mixture of peptides from the plurality of proteins; d) performing a first mass spectrometry on the mixture of peptides from the plurality of proteins to identify a plurality of mass isotopomeric envelopes of an initial series of ionic fragments representing individual proteins; e) performing a second mass spectrometry to identify secondary fragments of the initial series of ionic fragments; f) comparing the initial series of ionic fragments identified by the first mass spectrometry with the secondary fragments identified by the second mass spectrometry to identify one or more of the individual proteins in the sample; g) quantifying relative and absolute mass isotopomer abundances of the ionic fragments of one or more of the identified individual proteins within the mass isotopomeric envelope; and h) calculating the molecular flux rates of one or more of the identified individual proteins to determine the molecular flux rates of said plurality of proteins.