title: Flexibility of smooth and skeletal tropomyosins.
abstract: The rotational relaxation times of nonpolymerizable skeletal and smooth muscle tropomyosin were measured by analysis of the decay of the zero-field birefringence at different temperatures and salt concentrations. Skeletal tropomyosin in solution is equally well modeled as a rigid rod or as a semiflexible rod with a persistence length of 150 nm. Smooth muscle tropomyosin does not fit the rigid rod model but is well approximated by a semiflexible rod model with a persistence length of 55 nm. The results indicate that smooth muscle tropomyosin is either a more flexible molecule than skeletal muscle tropomyosin or is a curved structure with an end-to-end length shorter than the coiled-coil contour length. Smooth muscle tropomyosin controls the actomyosin ATPase differently from skeletal muscle tropomyosin and it had been suggested that the reason is because it is more rigid; clearly, another explanation must be sought.
authors.forename: C A
authors.initials: CA
authors.lastname: Swenson
authors.forename: N C
authors.initials: NC
authors.lastname: Stellwagen
mesh_terms: D000818:Animals; D001718:Birefringence; D005895:Gizzard, Avian / Q000378:metabolism; D009130:Muscle, Smooth / Q000378:metabolism; D009132:Muscles / Q000378:metabolism; D011487:Protein Conformation; D011817:Rabbits; D014335:Tropomyosin; D014422:Turkeys
chemical_list: D014335:Tropomyosin