Figure 3.

Overview of identification and validation of cross-linked peptides by mass spectrometry and database searching. A, B, Am, and Bm: free peptides A and B and peptides A and B modified by the cross-linker in the form of a γ-lactam. M_A, M_B, M_Am, and M_Bm: Masses of peptides A and B and their γ-lactam modifications. M_P: precursor mass. f_assigned: total number of assigned fragment ions. f_total: total number of fragment ions of highest intensity taken into account with a minimum of 10 and a maximum of 40 fragments. total_decoy: total number of assigned decoy peptides. total_target: total number of assigned target peptides.