Azide-A-DSBSO crosslinker is a mass spectrometry (MS) cleavable, membrane permeable, homobifunctional, azide-labeled, acid-cleavable crosslinking peptide. Azide-A-DSBSO crosslinker crosslinks proteins via NHS ester reaction with lysine residues. Azide-A-DSBSO crosslinker can be used to study protein-protein interactions by cross-linking mass spectrometry (XL-MS).