1: Biophys J  1995 Apr;68(4 Suppl):286S-289S; discussion 289S-290S 

Mechanical measurements of single actomyosin motor force.

Miyata H, Yoshikawa H, Hakozaki H, Suzuki N, Furuno T, Ikegami A, Kinosita K Jr,
Nishizaka T, Ishiwata S.

Department of Physics, Faculty of Science and Technology, Keio University,
Yokohama, Japan.

To elucidate the mechanism of force generation by actomyosin motor, a measuring
system was constructed, in which an in vitro motility assay was combined with an
optical trapping technique. An actin filament of several micron long was
attached to a gelsolin-coated polystyrene bead, and was allowed to interact with
a small number (approximately 1/1 micron actin filament) of rabbit skeletal
heavy meromyosin (an active subfragment of myosin) molecules bound to a
nitrocellulose-coated coverglass. The bead position was determined at 33-ms
intervals. We measured the force generation event at relatively low (100-400 nM)
ATP concentration so that the occurrence of individual force generation events
could be detected with our time resolution. The actin-bound bead held in the
optical trap moved in a stepwise manner in the direction of the actin filament
only in the presence of ATP. At the trap strength of 0.3 pN/nm, the maximum size
of the step was 11 nm, and the maximum force associated with the movement was
3.3 pN.

PMID: 7787092 [PubMed - indexed for MEDLINE]