S-(3-((4-((4-(2-((tert-Butoxycarbonyl)(4-hydroxy-3,5-diisopropylbenzyl)amino)acetamido)phenyl)diazenyl)phenyl)amino)-3-oxopropyl) Methanesulfonothioate is an intermediate used in the synthesis of MTS PHOTO-SWITCHABLE Compound (M125115), which is a derivative compound of Maleidoproponic Acid (M140750), a sulfhyryl reactive heterobifunctional crosslinking reagent.