has_neutral_loss_reporter has_reactive_group is_cleavable homofunctional cross-linker CID cleavable generic neutral loss reporter NHS ester BuUrBu -H2 -O1 -H3 -N1 12.5 196.0847919999999931 2 C9 H12 N2 O3 CID = : C9 H12 N2 O3 CID = C5 H7 N1 O2 : C4 H5 N1 O1 DSBU Disuccinimidyl dibutyric urea NHS-BuUrBu-NHS NHS-amino butyric acid-urea-amino butyric acid-NHS. XLMOD XLMOD:02120