Extinction Coefficient Excitation Maximum: 240600; Sulfo-Cy7 maleimide is water soluble cyanine dye containing a maleimide group which is commonly reacted with thiols to form a thioester bond at pH 6.5 to 7.5. This NIR dye amine can be used to derivate various targets by the reaction with electrophilic groups, and by enzymatical reactions involving transamination.