Sulfo-NHS-SS-Biotin is a primary amine (-NH2) reactive, water soluble, cleavable biotinylation reagent. Sulfo-NHS-SS-Biotin is routinely used to add biotin groups to a protein or peptide molecule. This compound can be added directly to aqueous buffer, and is cleavable in the presence of a reducing agent, such as TCEP, DTT, or 2-Mercaptoethanol.