2,5-Dioxopyrrolidin-1-yl nicotinate is an N-hydroxysuccinimide (NHS) ester of nicotinic acid, commonly used in bioconjugation and organic synthesis to introduce the nicotinate group onto amines. It reacts selectively with primary amines under mild aqueous conditions to form stable amide bonds, making it ideal for labeling proteins, peptides, and other biomolecules. This compound is particularly valuable in pharmaceutical research for developing targeted therapies, such as antibody-drug conjugates, and in the preparation of nicotinic acid derivatives for drug development. Its applications extend to studying biological interactions through site-specific modifications.