METHOD FOR DETECTING MASS CHANGE IN MASS SPECTROMETRY METHOD AND METHOD FOR QUANTIFYING ABSOLUTE AMOUNT OF STABLE ISOTOPE-LABELED PROTEIN
Conventional highly sensitive protein quantification methods using a spectrometer had the issue of sample loss and non-fragmentation rates during the process of fragmentation of the target protein not being corrected by internal standard peptide fragments. In addition, identification and/or quantification of posttranslational modification etc., of proteins using a spectrometer was extremely difficult. The present invention addresses the problem of developing a method for high-precision quantification of proteins using a spectrometer and identification and/or quantification of posttranslational modifications or genetic mutations in proteins. The present inventors found that a plurality of target protein-derived peptide fragments can be detected at one time using the spectrometer and proteins can be quantified with high sensitivity and high precision, by using a stable isotope-labeled, internal standard protein. The present inventors also found that the posttranslational modifications and genetic mutations of each peptide fragment could be identified and/or quantified using the average quantification value for the detected target protein-derived peptide fragments.