  Molecular motors are found throughout the cells of the human body, and have
many different and important roles. These micro-machines move along filament
tracks, and have the ability to convert chemical energy into mechanical work
that powers cellular motility. Different types of motors are characterized by
different duty-ratios, which is the fraction of time that a motor is attached
to its filament. In the case of myosin II - a non-processive molecular machine
with a low duty ratio - cooperativity between several motors is essential to
induce motion along its actin filament track. In this work we use statistical
mechanical tools to calculate the duty ratio of cooperative molecular motors.
The model suggests that the effective duty ratio of non-processive motors that
work in cooperation is lower than the duty ratio of the individual motors. The
origin of this effect is the elastic tension that develops in the filament
which is relieved when motors detach from the track.
