Diffusion Process of Myosin and Utilization of ATP Energy in F-Actin Solution

Theoretical calculation has been made on the problem of random flights of myosin particle, where it is assumed that individual myosin particle can slide on F-actin filament along its long axis during F-actin activated ATP hydrolysis and then diffuse freely in the aqueous solution. The apparent diffusion coefficient of such myosin particles is formulated as D = D 0 (1- f )+(1/9) L 0 V f , where D 0 is the diffusion coefficient of the free particles in the absence of ATP and F-actin, f is the fraction of the particles bound on F-actin filaments, L 0 is the average length of F-actin, and V is the sliding velocity of the particles on F-actin filaments. It is suggested that the sliding velocity V can be estimated experimentally on the basis of the above equation. An equivalent but more generally applicable equation than the above equation has also been derived by solving the Brownian motion of myosin particle described by the Langevin's equation. The factors which influence on efficiency of the energy transformation from chemical to mechanical are discussed.