Patent ID: 7045296
Filing Date: 2006-05-16
Classification: G01N,Y10S,Y10T

Abstract:
1. A method of comparing protein compositions of interest between at least two different samples which comprises: (a) preparing an extract of proteins from each of said at least two different samples; (b) providing a set of substantially chemically identical and differentially isotopically labeled protein reagents, wherein said reagent has a formula selected from the group consisting of: wherein A is an affinity label that selectively binds to a captive reagent, L is a linker group in which one or more atoms are differentially labeled with one or more stable isotopes and PRG is a protein reactive group that selectively reacts with a given protein functional group or is a substrate for an enzyme; (c) reacting the extract proteins from different samples of step (a) with a different isotopically labeled reagent from said set of step (b) to provide two or more sets of isotopically differentially labeled proteins; (d) mixing each of said two or more sets of isotopically differentially labeled proteins to form a single mixture of isotopically differentially labeled proteins; (e) separating two or more differentially labeled proteins in the mixture of step (d) by electrophoresing said mixture; (f) digesting at least a portion of the proteins that have been subjected to electrophoresis in step (e) to produce a sample of labeled peptides; and (g) detecting the difference in the expression levels of one or more differentially labeled proteins in the at least two different samples by mass spectrometry based on one or more differentially labeled peptides in the sample of labeled peptides.