| Popis: |
Molecular motors are enzymes that perform work (F · x) when they move along a track a distance x against a constant force F. This work is performed through intermediate chemical steps in a motor’s ATPase reaction cycle, each step having a free energy change associated with it that is a sum of chemical, Δµchem, and mechanical, Δµext, potentials. Defining Δµext is fundamental to our understanding of how molecular motors work, yet after decades of study the definition of Δµext remains disputed. Some postulate that Δµext is a function of both F and x, while others assume that Δµext is a function of neither F nor x, and still others argue that Δµext is a function of F but not x. Here we evaluate these models and conclude that only the latter – a mechanochemical model proposed by A.V. Hill in the 1930’s – describes molecular motor mechanochemistry. |
