Berlin 2005 – scientific programme

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AKB: Biologische Physik

AKB 55: Molecular Motors

AKB 55.1: Invited Talk

Tuesday, March 8, 2005, 14:00–14:30, TU H2013

The Role of Diffusion in the Mechanism of Motor Proteins - Thermal Ratchets and all that — •Jonathon Howard — Max Planck Institute for Molecular Cell Biology and Genetics

Motor proteins such as myosin, dynein and kinesin are enzymes that convert chemical energy, derived from the hydrolysis of ATP, into mechanical work used to power cellular motility. These proteins are unusual engines because the conversion into mechanical energy is direct rather than via an intermediate such as heat or electrical energy, as in everyday engines. A key concept for understanding the mechanism of energy transduction by motor proteins is the lever. Small, atom-sized conformational changes in the ATP-binding pocket of the protein (a few Angstroms) are amplified ten- to one hundred-fold into large conformational changes of the whole protein (several nanometers). The amplification is achieved via rigid-body rotations and translations of comparatively rigid protein domains. The transition between different chemical states is activated by thermal energy. In the case of motor proteins the transition is associated with large displacements corresponding to the protein conformational changes; for this reason, diffusion is expected to play an important role in the motor reaction. I discuss recent experimental and theoretical work on this question.