Phalloidin–Atto 550

Atto 550 is a new label with high molecular absorption (120.000) and quantum yield (0.80) as well as sufficient stoke′s shift (excitation maximum 554 nm, emission maximum 576 nm). Atto 550 can be used with similar excitation source and fluorescence filters as Cy3 TM and is characterized by a high photostability.Phalloidin is a fungal toxin isolated from the poisonous mushroom Amanita phalloides. Its toxicity is attributed to the ability to bind F actin in liver and muscle cells. As a result of binding phalloidin, actin filaments become strongly stabilized. Phalloidin has been found to bind only to polymeric and oligomeric forms of actin, and not to monomeric actin. The dissociation constant of the actin-phalloidin complex has been determined to be on the order of 3 x 10–8. Phalloidin differs from amanitin in rapidity of action; at high dose levels, death of mice or rats occurs within 1 or 2 hours.

Fluorescent conjugates of phalloidin, rhodamine-phalloidin staining reagents, such as Phalloidin–Atto 550 are used to label actin filaments for histological applications. Some structural features of phalloidin are required for the binding to actin. However, the side chain of amino acid 7 (g-dihydroxyleucine) is accessible for chemical modifications without appreciable loss of affinity for actin.

This product is for Research use only. In case of intended commercialization, please contact the IP-holder (ATTO-TEC GmbH, Germany) for licensing.