• Highly reactive NHS ester (at both ends) with primary amines
• MS-cleavable by collision-induced dissociation (CID)
• High-purity crystalline reagents for protein structure and interaction characterization
• Membrane-semi-permeable, allowing intracellular crosslinking
• Water-insoluble (dissolve first in DMF or DMSO)

DSSO (disuccinimidyl sulfoxide) and DSBU (disuccinimidyl dibutyric urea) (or BuUrBU) are both MS-cleavable and membrane-semi-permeable crosslinkers that contain an amine-reactive N-hydroxysuccinimide (NHS) ester at each end of a 7-carbon spacer arm (DSSO) or 11-atom spacer arm (DSBU). Both crosslinkers have similar reactivity to DSS but contain a cleavable functionality in the linker region that enables cleavage in the gas phase using collision-induced dissociation (CID) during tandem MS (MS/MS) fragmentation. The MS cleavage of DSSO or DSBU generates diagnostic ion doublets during MS2, which distinguishes identification of cross-linked peptides from dead-end modifications. The crosslinked peptide fragments are subsequently identified using MeroX or XlinkX software. For DSSO, cleavage of cross-linked peptides during MS/MS enables MS3 acquisition methods, which additionally facilitates peptide sequencing using traditional database search engines.

Note: For high resolution analysis of the crosslinked peptides, the recommended LC column for the Nanospray Flex source is the Acclaim PepMap 100 C18 LC Column (Cat. No. 164940 or 164568). For the EASY-Spray source, the recommended LC column is the EASY-Spray C18 LC Column (Cat. No. ES900 or ES904).