Actin-myosin interaction in oriented F-actin filament system

The decorated actin technique combined with the spin label method was used to study the interaction of skeletal muscle actin and myosin in synthetic filament system. If follows from the orientation dependence of the EPR spectra of the rigidly attached spin label in F-action filaments that the spin-label is sensitive to the dynamic state of the filaments. The interaction of myosin heads with actin reduces the intrinsic order of the F-actin filaments. The interaction seems to be cooperative.