Photoaffinity labeling of benzophenone-containing salicylanilide compounds to give an insight into the mechanism in disrupting peptidoglycan formation

•A. baumannii PBP1b is photo-labeled by a benzophenone-containing salicylanilide (1).•Trypsin digestion and LC–ESI-MS2 analysis reveal a labeled R364–R381 octadecapeptide.•Molecular docking shows that 1 resides in R367–E372 surrounded hydrophobic pocket.•The hydrophobic pocket is located between the TGase and TPase domains of PBP1b.•Binding of 1 in the R367–E372 pocket disrupts the growth of peptidoglycan chain.