Effect of electric field on F-actin oriented by flow

Pulsed electric fields were applied to F-actin oriented by flow and the process of dis- orientation was followed by birefringence measurements. An electric field parallel to the filament axis of F-actin produced a large disorientation effect whereas a perpendicular field produced a small effect. The analysis of the birefringence decrease in normal and reversed pulses at various field strengths suggests that F-actin has a large permanent dipole moment perpendicular to the filament axis. The marked disorientation effect of the parallel field on F-actin vanished on addition of H-meromyosin. On dissociation of the complex of F-actin and H-meromyosin by the addition of ATP the disorientation effect of the parallel field was again observed. This result suggests that a strong electric interaction exists between (permanent) dipoles of F-actin and H-meromyosin.