Succinimidyl 6-[3-(2-Pyridyldithio)propionamido]hexanoate

SPDP-C6-NHS ester contains a disulfide bond which is cleavable upon reduction. The NHS ester is reactive toward primary amine and sulfhydryl groups. SPDP-C6-NHS ester is commonly used for bioconjugation and reversible crosslinkings.

White Solid

A sulfhydryl and amino reactive heterobifunctional protein crosslinking reagent.

The amine-reactive portion of SPDP reagents is the N-hydroxysuccinimide (NHS) ester. Reactions are most commonly performed in phosphate, carbonate/bicarbonate, or borate buffers at pH 7-8. Other buffers can be used provided they do not contain primary amines (or thiols or disulfide reducing reagents – see discussion of the sulfhydryl reactivity). The rate of reaction and degradation by hydrolysis increases with increasing pH; for example, the half-life of the NHS ester is several hours at pH 7 and less than 10 minutes at pH 9. NHS-ester reagents like SPDP and LC-SPDP have limited aqueous solubility and must be dissolved in organic solvent before adding them to a reaction mixture. Sulfo-NHS-ester reagents like Sulfo-LC-SPDP are water-soluble and can be added directly to aqueous reaction mixtures.