Fura-2, AM ester is a ratiometric fluorescent dye that binds to free intracellular calcium, and is the preferred dye for ratiometric imaging microscopy. Fura-2, AM ester is membrane-permeant and thus can be loaded into cells via incubation. Because of the relatively low water solubility of the AM ester, the mild detergent Pluronic F-127 is often used as a dispersing agent to facilitate cell loading. Fura-2, AM ester itself does not bind Ca2 , but it is readily hydrolyzed to Fura-2 by endogenous esterases once it enters cells. Measure using flow cytometry, fluorescence microscopy, or certain fluoresence microplate readers. Upon calcium binding, the fluorescent excitation maximum of the indicator undergoes a blue shift from 363 nm (Ca2-free) to 335 nm (Ca2-saturated), while the fluorescence emission maximum is relatively unchanged at ~510 nm.    A major use of Fura-2 is in drug discovery, for measuring intracellular calcium mobilization after activation of G protein-coupled receptors (GPCRs) and calcium channels.    Light yellow solid soluble in DMSO  Store at -20°C and protect from light, especially in solution  Kd: 145 nM (22°C in pH 7.2 buffer)  &lamba; Ex/&lamba;Em (no Ca2) = 363/512 nm; &lamba; Ex/&lamba; Em (high Ca2) = 335/505 nm  ε (363 nm, no Ca2) = 27,000 M-1cm-1; ε (335 nm, high Ca2) = 35,000 M-1cm-1  C44H47N3O24  MW: 1001.9  [108964-32-5]