Stochastic action of actomyosin motor

It is argued that the actomyosin motor can be effectively considered a common chemo-chemical enzymatic machine occurring, however, in multitude rather than a few conformational substates distinguished by the conventional kinetics. A technique was developed with the help of which relations were found between basic parameters of the machine's flux-force dependences: the turnover number, the force stalling the motor as well as the degree of coupling between the ATPase and the mechanical cycles, and the mean first-passage times in a random movement between some distinguished conformational substates of the myosin head. The phenomenology proposed is consistent with all presently available experimental data including multiple stepping per one adenosine triphosphate molecule hydrolysed. (C) 2004 Elsevier B.V. All rights reserved.