3,4-Dibromo-1H-pyrrole-2,5-dione - 5 G

3,4-Dibromo-1H-pyrrole-2,5-dione is a small pyrrolidone molecule which features two bromine atoms and a free nitrogen. The unsaturated dibromo motif is a covalent ligand for thiol groups, and may be used to label cysteine residues in proteins. The presence of two leaving groups on this molecule allows this linker to bind two thiols at a time. The central amine can be alkylated or linked with carboxylic acids to form larger compounds.