Fig. 1 Enzymatic labeling of stable isotope coding of proteomics
�@ Proteins from two distinct proteome are digested with protease in normal water or isotopically labeled water. Isotope code is labeled in every C-terminus of the digested peptides. Then, two samples are combined and analyzed by LC-MS/MS. Expression level of proteins between two states can be estimated. Amino acid sequence of selected peptide fragment can be identified, too.