title: Direct measurement for elasticity of myosin head.
abstract: During muscle contraction, chemical energy from ATP hydrolysis is converted to the relative sliding movement of actin and myosin filaments. In order to elucidate the molecular mechanism of sliding-force generation, it is a crucial clue to know an elastic modulus of myosin. Here, we report direct measurements of Young's modulus of myosin head (myosin subfragment-1) isolated from rabbit skeletal muscle, using a surface forces apparatus. Our results show that the elasticity of myosin subfragment-1 has direction and is about 0.3 GPa along the long axis during ATP hydrolysis. When the bow-shaped subfragment-1 is modelled as an elastic rod, the stiffness and the bending fluctuations of subfragment-1 are calculated to be 3-7 pN/nm and about 1 nm, respectively. These results strongly support a model of multiple power strokes rather than the conventional tilting-crossbridge model.
authors.affiliation: Department of Biological Science and Technology, Tokai University, Shizuoka, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Suda
authors.forename: M
authors.initials: M
authors.lastname: Sugimoto
authors.forename: M
authors.initials: M
authors.lastname: Chiba
authors.forename: C
authors.initials: C
authors.lastname: Uemura
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D004548:Elasticity; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000378:metabolism; D015879:Myosin Subfragments / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D011817:Rabbits
chemical_list: D015879:Myosin Subfragments; D000255:Adenosine Triphosphate