Probing the phalloidin binding site of actin

Transient kinetic analysis of rhodamine phalloidin binding to actin filaments.

We have characterized the binding of rhodamine phalloidin to actin filaments and actin filaments saturated with either myosin subfragment-1 or tropomyosin in 50 mM KCl, 1 mM MgCl2 buffer at pH 7.0. Direct transient kinetic measurements of rhodamine phalloidin binding to actin filaments indicate an association rate constant of 2.8 x 10(4) M-1 s-1 and a dissociation rate constant of 4.8 x 10(-4) ...

PROBING THE ACTIVE SITE OF RHODANESE WITH DISULFIDE REAGENTS

Effects of cytochalasin and phalloidin on actin

C YTOCHALASINS and phalloidins are two groups of small, naturally occurring organic molecules that bind to actin and alter its polymerization. They have been widely used to study the role of actin in biological processes and as models for actin-binding proteins. Functionally , cytochalasins resemble capping proteins, which block an end of actin filaments, nucleate polymerization, and shorten fi...

Proximity relationships and structural dynamics of the phalloidin binding site of actin filaments in solution and on single actin filaments on heavy meromyosin.

Distance relationships between phalloidin binding sites on F-actin have been investigated using fluorescence resonance energy transfer (FRET) techniques in solution and on single F-actin filaments bound to heavy meromyosin (HMM). Filaments saturated with an equimolar concentration of fluoresceinisothiocyanatophalloidin (FITC-ph) as the donor and tetramethylrhodamineisothiocyanatophalloidin (TRI...

Kinetics and thermodynamics of phalloidin binding to actin filaments from three divergent species.

We compared the kinetics and thermodynamics of rhodamine phalloidin binding to actin purified from rabbit skeletal muscle, Acanthamoeba castellanii, and Saccharomyces cerevisiae in 50 mM KCl, 1 mM MgCl2, and pH 7.0 buffer at 22 degrees C. Filaments of S. cerevisiae actin bind rhodamine phalloidin more weakly than Acanthamoeba and rabbit skeletal muscle actin filaments due to a more rapid dissoc...