N-Succinimidyl 3-(2-pyridyldithio)propionate

N-Succinimidyl 3-(2-pyridyldithio)propionate is a heterobifunctional cross-linking reagent with amine and sulfhydryl reactivity. It is typically coupled initially to molecules containing primary amines by amide bonds buffered at pH 7.5 (6.5-8.5). Second coupling specific for molecules containing free sulfhydryl by thiol-disulfide exchange buffered at pH 8.0 (7.5-8.5). Alternately, this reagent may be used as a protected thiolating reagent following initial coupling and reduction of linker. It incorporates four atom linker. N-Succinimidyl 3-(2-pyridyldithio)propionate (SPDP) is useful for the preparation of enzyme immunoconjugates and hapten carrier molecule conjugates. It has been used for antibody conjugation and as a protein cross-linker. It is also a glutathione cleavable ADC linker used for the antibody-drug conjugates (ADCs).