HYDRODYNAMICAL RESISTANCE OF A SMOOTH-MUSCLE MYOSIN MOLECULE AND ITS APPLICATION TO CONFORMATIONAL-CHANGES ASSOCIATED WITH PHOSPHORYLATION

Hydrodynamical calculation of the drag and side forces on a single myo sin molecule in an incompressible viscous fluid, which is placed in an otherwise uniform flow along its rod direction, is made on the basis of the Stokes equation. The beads model approximation is employed to d escribe various conformation of the heads and tail of this macromolecu le. The results are compared with an electrophoretic measurement of an intact myosin of the smooth muscle in a pyrophosphate polyacrylamide gel. Biochemical analysis is combined to give the relation between the phosphorylation of the myosin regulatory light chains and the orienta tions of the two heads relative to the rod axis. Possible actin-and-my osin interaction mechanisms which may cause the smooth muscle contract ion are discussed.