Molecular Mass 1582.65 g/mol-1. ?Flash Phalloidin? Green 488 excites maximally at 488 nm and emits maximally at 520 nm.? Phalloidin is a bicyclic peptide that can be found naturally in the death cap mushroom.?This molecule is considered to bind so tightly to F-actin that when ingested by an organism, it will prevent the depolymerization of the actin polymeric filaments which leads to cellular toxicity.? In cell imaging, this is a very useful probe for imaging and stabilizing filamentous F-actin in fixed and permeabilized cells, providing structural and volumetric context to the cell.?Phallotoxins are conjugated to a wide array of fluorophores to enable their use in multicolor microscopy.