Tom Duke
Teaching
Miscellaneous
Motors at work: Motor proteins are the cell's workforce. They are specialized molecules which convert chemical energy to mechanical work, thereby generating force and directional motion. In some situations motor proteins act individually, but more commonly they cooperate in large ensembles to accomplish cellular functions. How do molecular motors work? And how do they work together? The methods of non-equilibrium statistical mechanics permit a general analysis of how chemical energy can most effectively be used to generate the movement of an individual motor. They also indicate what types of collective effects and dynamical instabilities can arise when many molecules operate in concert.
Muscle contraction: We have proposed a quantitative stochastic model of the mechanochemical cycle of myosin, the protein which drives muscle contraction. The model is based on structural observations which suggest that the head domain contains a swinging lever arm. It provides an explanation, at the molecular level, of many of the mechanical and thermodynamic properties of steadily shortening muscle. In particular, the inflexion in the force-velocity curve as the isometric load is approached is reproduced. Moreover, the model indicates that when large numbers of myosin molecules act collectively, their chemical cycles can be synchronized, and that this leads to stepwise motion. The oscillatory transient reponse of muscle to abrupt changes of load can be interpreted in this light.
