Regensburg 2002 – scientific programme

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SYBM: Physik biologischer Materie

SYBM VI: HV VI

SYBM VI.1: Invited Talk

Tuesday, March 12, 2002, 16:30–17:00, H37

Biomolecular Mechanics — •Matthias Rief, Ingo Schwaiger, and Anabel Clemen — Lehrstuhl fuer angewandte Physik der LMU Muenchen

Recent developments in piconewton instrumentation allow the mechanical manipulation of single molecules. Structural stability of individual biomolecules as well as the movement of single molecular motor molecules can be directly probed. We measured the forces required to unfold individual protein domains. We could show that the unfolding forces depend on the pulling velocity and on the protein topology. From the direct measurement of unfolding forces spatial information about the folding potential can be obtained. However, not only the passive mechanical properties of single biomolecules can be measured but ultrasensitive force-probes like optical tweezers can be used to observe the stepwise movement of individual molecular motors along their track. We show that from a statistical analysis of the stepping kinetics we can obtain insight into rate limiting transitions in the chemo-mechanical cycle of myosin V. This analysis strongly suggests that ADP release is the rate limiting step of the motor movement. We also present a hand-over hand model for myosin V processivity.