METHOD FOR QUANTIFYING OXIDIZED METHIONINE RESIDUE IN PROTEIN AND METHOD FOR DETERMINING POSITION THEREOF

摘要

It is intended to provide a method capable of determining the oxidation degree of methionine residue in a protein or peptide and a method capable of determining the position of an oxidized methionine residue. The method for quantifying an oxidized methionine residue in a protein comprises (i) preparing a protein sample A in which the oxidation degree of methionine residue is unknown and preparing a protein sample B in which the oxidation degree of methionine residue is unknown, (ii) obtaining a modified protein sample A’ by modifying a methionine residue using either one of a heavy reagent and a light reagent used in the isotope labeling method against the protein sample A and separately obtaining a modified protein sample B’ by modifying a methionine residue using the other of the heavy reagent and the light reagent against the protein sample B, (iii) obtaining a sample mixture for mass analysis by mixing the modified protein sample A’ and the modified protein sample B’, and (iv) subjecting the sample mixture for mass analysis to mass analysis and quantifying the oxidation degree of methionine residue in each of the protein sample A and the protein sample B.