ELASTICALLY COUPLED MOLECULAR MOTORS

We study the influence of filament elasticity on the motion of collect ive molecular motors. It is found that for a backbone flexibility exce eding a characteristic value (motor stiffness divided through the mean displacement between attached motors), the ability of motors to produ ce force reduces as compared to rigidly coupled motors, while the maxi mum velocity remains unchanged. The force-velocity-relation in two dif ferent analytic approximations is calculated and compared with Monte-C arlo simulations. Finally, we extend our model by introducing motors w ith a strain-dependent detachment rate. A remarkable crossover from th e nearly hyperbolic shape of the Hill curve for stiff backbones to a l inear force-velocity relation for very elastic backbones is found. Wit h realistic model parameters we show that the backbone flexibility pla ys no role under physiological conditions in muscles, but it should be observable in certain in vitro assays.