Phalloidin–Atto 655

Atto 655 belongs to a new generation of fluorescent labels. The dye is designed for application in the area of life science, e.g. labeling of DNA, RNA or proteins. Characteristic features of the label are strong absorption, good fluorescence quantum yield, excellent thermal and photo-stability, outstanding ozone resistance, very good water solubility, and very little triplet formation. Atto 655 is a zwitterionic dye with a net electrical charge of zero. The fluorescence is efficiently quenched by electron donors like guanine, tryptophan, etc.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 655 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.