  We propose a biochemical model providing the kinetic and energetic
descriptions of the processivity dynamics of kinesin and dinein molecular
motors. Our approach is a modified version of a well known model describing
kinesin dynamics and considers the presence of a competitive inhibition
reaction by ADP. We first reconstruct a continuous free-energy landscape of the
cycle catalyst process that allows us to calculate the number of steps given by
a single molecular motor. Then, we calculate an analytical expression
associated to the translational velocity and the stopping time of the molecular
motor in terms of time and ATP concentration. An energetic interpretation of
motor processivity is discussed in quantitative form by using experimental
data. We also predict a time duration of collective processes that agrees with
experimental reports.
