| abstract |
The presence or absence of a modifying group or the type of the modifying group at a specific amino acid residue in a protein is conveniently determined. A protein to be analyzed is treated with a reagent capable of labeling a side chain of a specific amino acid residue. In the case where the side chain of the specific amino acid residue is unmodified, the side chain is labeled (S101). Next, the protein, in which the side chain of the specific amino acid residue has been labeled, is specifically cleaved at a definite site (S102). Subsequently, the obtained peptide fragment is subjected to mass spectroscopy (S103). Based on the molecular weight data of the fragment thus obtained, the modified state of the side chain of the specific amino acid residue in the protein to be analyzed is analyzed (S104). |