Visualization of Local Winding Propagations on an Actin Filament in anin vitroMotility Assay System

Abstract

Observation images of movements of muscle proteins at the molecular level contain detailed information on the chemical reactions involving the proteins. If we can distinguish reaction-related movement from thermal fluctuations, we can visualize genesis locations of chemical reactions. Therefore, we tried to extract coordinated movement distinguished from thermal fluctuation in movement of an actin filament in anin vitromotility assay system to visualize chemical reaction by muscle protein. We extracted the possible skeletal structure of an actin filament by image analysis and visualized local propagation vectors of windings from the propagation direction and propagation velocity of the windings determined by correlation analysis. By using this method, we could find that the propagation distance and velocity of windings from the tail-end to the head-end of the filament showed the tendency to increase as the ATP concentration increased. On the other hand, those from the head-end to the tail-end were independent of ATP concentration. These results mean that these windings have a significant relationship to ATP hydrolysis; especially, the generating points of these windings include significant information.