Flexibility of smooth and skeletal tropomyosins.
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.
Swenson
C A
CA
Stellwagen
N C
NC
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
D014335:Tropomyosin