Parameter 

Ex/Em: 546/575 nm

Storage 

Store at -20°C and protect from light. Expiration date marked on the outer packing..

Description 

Phalloidin is a bicyclic peptide that belongs to a family of toxins isolated from the deadly Amanita phalloides mushroom. It is a very convenient tool to investigate the distribution of F-actin when labeled with fluorescent dyes. Phalloidin contains an unusual thioether bridge between cysteine and tryptophan residues that forms an inner ring structure. At elevated pH, this thioether is cleaved and the toxin loses its affinity for actin.

Labeled phalloidins have similar affinity for both large and small filaments, binding in a stoichiometric ratio of about one phalloidin molecule per actin subunit in muscle and nonmuscle cells from various species of plants and animals. Different from antibodies, the binding affinity of phalloidin does not change significantly with actin among different species. Non-specific staining is negligible, and the contrast between stained and unstained areas is extremely large. Phalloidin shifts the monomer/polymer equilibrium toward the polymer, lowering the critical concentration for polymerization up to 30-fold. Phallotoxins also stabilize F-actin, inhibiting depolymerization by cytochalasins, potassium iodide and elevated temperatures. Because the phalloidin conjugates are small, with an approximate diameter of 12–15Å and molecular weight of <2000 Daltons, a variety of actin-binding proteins including myosin, tropomyosin and troponin can still bind to actin after treatment with phalloidin. Even more significantly, phalloidin-labeled actin filaments remain functional; labeled glycerinated muscle fibers still contract, and labeled actin filaments still move on solid-phase myosin substrates. Fluorescent phalloidin can also be used to quantify the amount of F-actin in cells.

Notes 

This product is is lyophilized solids, and it is difficult to observe the trace amount. Please centrifuge before use, and add appropriate solvent to dissolve it. The solution after dissolution is almost transparent.If dissolved in water, freeze in aliquots.