Rhod 2 has the longest fluorescent wavelength signal of all the calcium indicators. It has a rhodamine-like fluorophore whose excitation and emission maxima are 557 nm and 581 nm, respectively. This makes it a convenient excitation source for argon and krypton lasers. Although it was thought that the fluorescent signal of Rhod 2 only increases several times with the calcium complex, Dojindo’s Rhod 2 increases its signal with calcium 80-100 times because of its high purity. Its signal intensity is the strongest of all the calcium probes. Rhod 2 is thus highly recommended as a probe for intracellular calcium monitoring using laser microscopes. Rhod 2 is reported to have a better loading profile at the point of localization, especially in neural slice cultures. The dissociation constant of Rhod 2 with calcium (Kd=1.0 mM) is the highest of all the fluorescent calcium probes, providing a wider range for monitoring calcium concentration. Rhod 2-AM is an acetoxymethyl ester derivative of Rhod 2 that can be easily loaded into cells using the AM method.
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