Sulfo-SMPB (sulfosuccinimidyl 4-(N-maleimidophenyl)butyrate)

SMPB and its water-soluble analog Sulfo-SMPB are heterobifunctional crosslinkers that contain N-hydroxysuccinimide (NHS) ester and maleimide groups that allow covalent conjugation of amine- and sulfhydryl-containing molecules. NHS esters react with primary amines at pH 7-9 to form amide bonds, while maleimides react with sulfhydryl groups at pH 6.5-7.5 to form stable thioether bonds. In aqueous solutions, hydrolytic degradation of the NHS ester is a competing reaction whose rate increases with pH. The maleimide group is more stable than the NHS-ester group but will slowly hydrolyze and also lose its reaction specificity for sulfhydryls at pH values > 7.5. For these reasons, conjugation experiments involving these crosslinkers are usually performed at pH 7.2-7.5, with the NHS-ester (amine-targeted) reaction being accomplished before or simultaneous with the maleimide (sulfhydryl-targeted) reaction.

This product is sensitive to moisture. The vial is packaged in a resealable bag with a desiccant to reduce exposure to moisture. After cold storage, equilibrate the vial to room temperature before opening to reduce condensation inside the vial. Make fresh solutions. Storage of stock solutions is not recommended. After use, return the vial to the resealable bag. Close the bag and store the product at the recommended temperature.