title: Single turnovers of fluorescent ATP bound to bipolar myosin filament during actin filaments sliding.
abstract: The nucleotide turnover rates of bipolar myosin thick filament along which actin filament slides were measured by the displacement of prebound fluorescent ATP analog 2'(3')-O-[N-[2-[(Cy3)]amindo]ethyl] carbamoyl]-adenosine 5' triphosphate (Cy3-EDA-ATP) upon flash photolysis of caged ATP. The fluorescence of the thick filament where actin filament slides decayed with two exponential processes. The slower rate constant was the same as that without actin filament. Along bipolar myosin thick filament, actin filaments slide at a fast speed towards the central bare zone (forward), but more slowly away from the bare zone (backward). The displacement rate constant of fluorescent ATP from the myosin filament where actin filament moved forward was 5.0 s(-1), whereas the rate constant where the actin filament slid backward was 1.7 s(-1). These findings suggest that the slow ADP release rate is responsible for the slow backward sliding movement.
authors: Department of Integrated Sciences in Physics and Biology, College of Humanities and Sciences, Nihon University, Sakurajosui, Setagaya-ku, Tokyo 156-8550, Japan.
authors: Takahiro
authors: T
authors: Maruta
authors: Department of Integrated Sciences in Physics and Biology, College of Humanities and Sciences, Nihon University, Sakurajosui, Setagaya-ku, Tokyo 156-8550, Japan.
authors: Takahiro
authors: T
authors: Kobatake
authors: Department of Integrated Sciences in Physics and Biology, College of Humanities and Sciences, Nihon University, Sakurajosui, Setagaya-ku, Tokyo 156-8550, Japan.
authors: Hiroyuki
authors: H
authors: Okubo
authors: Department of Integrated Sciences in Physics and Biology, College of Humanities and Sciences, Nihon University, Sakurajosui, Setagaya-ku, Tokyo 156-8550, Japan.
authors: Shigeru
authors: S
authors: Chaen
keywords: ADP release; caged-ATP; in vitro motility assay; nucleotide displacement