However, trypsin is unable to cleave after a citrulline residue which is neutral. A missed cleavage after a citrulline residue together with the correct mass shift can be used as a specific and sensitive marker for citrullination, and the strategy is compatible with standard bottom-up proteomics workflows.
Because trypsin cannot cleave after a citrulline residue (which is neutral), a missed cleavage at this site, along with a proper mass shift, serves as a reliable and sensitive indicator of citrullination. This method can be easily integrated into existing bottom-up proteomics workflows.