Force Dependence of the Michaelis Constant in a Two-State Ratchet Model   for Molecular Motors
  We present a quantitative analysis of recent data on the kinetics of ATP hydrolysis, which has presented a puzzle regarding the load dependence of the Michaelis constant. Within the framework of coarse grained two-state ratchet models, our analysis not only explains the puzzling data, but provides a modified Michaelis law, which could be useful as a guide for future experiments. 
Gianluca Lattanzi and Amos Maritan