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

General Description

SPB is an amine-reactive and photoreactive heterobifunctional crosslinking reagent. The photoreactive psoralen group provides much greater covalent insertion yields than phenyl azide-containing compounds, which makes this reagent a superior alternative to typical photoreactive NHS-ester crosslinkers. The psoralen tricyclic planar ring system intercalates into double-stranded, and to a lesser extent, single-stranded, DNA, RNA, PCR products, cDNA or oligonucleotides. It also can be used with agarose gel-purified oligonucleotides because the presence of agarose does not interfere with the coupling reaction. The nucleic acid labeling site of the psoralen group (the 5,6 double bond in thymine residues) does not interfere with subsequent hybridization reactions, creating a highly-sensitive direct labeling alternative to radioactive probes.