Fig. 2 N-terminus chemical labeling of stable isotope coding of proteomics
　 Proteins from two distinct proteome are digested with protease, then the digested peptides in each sample are labeled with H4-reagent or D4-reagent, respectively. Then, two samples are combined and analyzed by MALDI-MS/MS. Expression level of proteins between two states can be estimated. Amino acid sequence of selected peptide fragment can be identified, too.