Chemical derivatization of peptides for quantitative proteomics

Modern mass spectrometry-based proteomics increasingly relies on quantitative workflows for many applications ranging from the development of new proteomic techniques to applications in biology and biomedicine. To achieve the goal of robust, sensitive and accurate quantitative proteomics methods, chemical derivatization has been used for more than two decades, with a strong emphasis on differential stable isotope labeling. This chapter summarizes the state of the field in mass difference and isobaric labeling methods based on chemical tags and introduce the underlying concepts related to instrumentation and bioinformatics. In addition, selected examples will be highlighted for successful applications of these derivatization methods, including the recently emerging area of single-cell proteomics that heavily relies on chemical labeling.