Thermo Scientific™ SPB (succinimidyl-[4-(psoralen-8-yloxy)]-butyrate)

SPB (succinimidyl-[4-(psoralen-8-yloxy)]-butyrate) is covered under our general 1-year warranty and is guaranteed to be fully functional for 12 months from the date of shipment, if stored as recommended. Please see section 8.1 of our Terms & Conditions of Sale (https://www.thermofisher.com/content/dam/LifeTech/Documents/PDFs/Terms-and-Conditions-of-Sale.pdf) for more details.

We offer the following crosslinkers for protein to nucleic acids: formaldehyde (Cat. No. 28906), SPB (Cat. No. 23013), SDAD (Cat. No. 26169), sulfo-SDAD (Cat. No. 26175), and sulfo-SBED (Cat. No. A39260).
Formaldehyde can be used for DNA-DNA crosslinking as well as DNA-protein crosslinking. While it is good for crosslinking proteins that are in direct contact with DNA, formaldehyde cannot link proteins that may be bound in a complex with other proteins but are not in direct contact with DNA. EGS or DSG can crosslink proteins to other proteins that are in direct contact with DNA and crosslinked to DNA by formaldehyde.
SPB, Sulfo-SDAD, and Sulfo-SBED are all photoreactive crosslinkers. SPB is an NHS-ester and psoralen heterobifunctional crosslinker that conjugates primary amines on proteins to DNA via photo-activated intercalation of psoralen to pyrimidine bases. The psoralen tricyclic planar ring system intercalates into double-stranded, and to a lesser extent, single-stranded DNA and RNA. The photoreactive psoralen group provides more selective covalent binding to nucleic acids than either phenyl azide or diazerine linkers, which makes SPB the best choice. The diazerine on sulfo-SDAD and the phenyl azide on sulfo-SBED are not selective for nucleic acids and can crosslink other biomolecules in the same besides any protein-DNA interactions. Sulfo-SBED involves biotin transfer rather than actual linking.