Hydrodynamical Analysis of Electrophoretic Measurement and the Determination of the Conformation of a Myosin Molecule

Osamu Sano¹ and Hiromi Takano-Ohmuro²

¹Department of Physics, Faculty of General Education, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183, Japan
²Tokyo Metropolitan Institute of Medical Sciences. Bunkyo-ku. Tokyo 113, Japan

(Received December 20, 1990; Accepted February 5, 1991)

Keywords: Myosin, Conformational Change, Beads Model, Phosphorylation, Muscle Contraction

Abstract. Hydrodynamical calculation of the mobility of a myosin or a heavy meromyosin molecule in an incompressible viscous fluid is made on the basis of the Stokes equation. The beads model approximation is employed to describe various conformation of the heads and tails of these macromolecules. The drag and side forces are computed, which are exerted to these models when placed in an otherwise uniform flow along their rod directions. These results are compared with an electrophoretic measurement in a pyrophosphate polyacrylamide gel, by which orientations of the two heads relative to the rod axis are determined. Conformational changes of an intact myosin of the smooth muscle associated with phosphorylation of its regulatory light chain are discussed in connection with its muscle contraction.