1: Nature  1995 Sep 21;377(6546):251-4 

Unbinding force of a single motor molecule of muscle measured using optical
tweezers.

Nishizaka T, Miyata H, Yoshikawa H, Ishiwata S, Kinosita K Jr.

Department of Physics, School of Science and Engineering, Waseda University,
Tokyo, Japan.

The unbinding and rebinding of motor proteins and their substrate filaments are
the main components of sliding movement. We have measured the unbinding force
between an actin filament and a single motor molecule of muscle, myosin, in the
absence of ATP, by pulling the filament with optical tweezers. The unbinding
force could be measured repeatedly on the same molecule, and was independent of
the number of measurements and the direction of the imposed loads within a range
of +/- 90 degrees. The average unbinding force was 9.2 +/- 4.4 pN, only a few
times larger than the sliding force but an order of magnitude smaller than other
intermolecular forces. From its kinetics we suggest that unbinding occurs
sequentially at the molecular interface, which is an inherent property of motor
molecules.

PMID: 7675112 [PubMed - indexed for MEDLINE]