The effect of phallotoxins on the structure of F-actin in myosin-free ghost muscle fibres of rabbit.

Using polarized UV fluorescent microscopy it has been shown that phallotoxins (phalloidin-sulfone, phalloidin-sulfoxide-B, phalloidin-sulfoxide-A and dithio-phalloidin) cause an increase in tryptophan fluorescence anisotropy of F-actin myofilaments in myosin-free ghost muscle fibres of rabbit. The results obtained are considered to be evidence of conformational changes in F-actin, induced by phallotoxins. These changes are irreversible to a significant extent, which points to a high degree of actin binding to both toxic and nontoxic phallotoxins.