Local Migration of Myosin in F-Actin plus ATP Solution on"the Boundary of a Diffusion Cell1

The diffusion phenomena of myosin (myosin A, H-meromyosin or subfragment-1) in\F-actin plus ATP solutions were investigated. The upper part of the diffusion cell was filled with F-actin plus ATP, and the lower part was filled with F-actin, ATP, and myosin, then both parts were brought into contact so that a boundary of the two solutions was formed and the diffusion of myosin in F-actin plus ATP solutions started. The diffusion pattern was observed with a schlieren lens system. When almost all the ATP in the lower part of the cell had been consumed by actomyosin, a hyper-sharp schlieren pattern appeared near the boundary. On analyzing this pattern, it was found that a local fast migration of proteins was occurring. Simple Brownian motion of myosin molecules could not explain the hyper-sharp phenomenon. This phenomenon occurred in ther pesence of Mg1+ or Caf+, but very little in the presence of EDTA. Although it is well known that the superprecipitation of myosin B suspension occurs only at physiological ionic strength, this phenomenon occurred over a relatively wide range of ionic strengths. The molecular mechanism of this phenomenon is discussed in relation to the basic mechan-ism of the interaction between myosin and F-actin. The phenomenon of superprecipitation of myosin muscular contraction was proposed on the basis of B suspensions was discovered by Szent-Gyorgyi interference microscopic observations (2), electron (7) and has been regarded as an in vitro model of microscopic observations (3, 4), low-angle X-ray muscular contraction. The sliding theory of diffractive observations (5), and phase-contrast microscopic observations (6), etc. This hypothesis is that the contraction of striated muscle occur