N-(2-Hydroxyethyl)maleimide

N-(2-Hydroxyethyl)maleimide is a maleimide conjugation reagent designed for thiol-reactive coupling. The maleimide group provides a selective handle for sulfhydryl-containing molecules, while the opposite terminus and spacer determine how the reagent can be connected to a payload, linker intermediate, or additional functional module. The molecule incorporates maleimide-containing spacer; exact linker length depends on structure and provides opposite-end functionality not fully defined from the name; maleimide itself is typically reserved for antibody thiol conjugation on the opposite side. It can be used in stepwise conjugation workflows that combine thiol-maleimide coupling with an orthogonal second reaction, with reaction order selected to suit the stability and accessibility of each functional group.