Abstract
Low-angle X-ray diffraction measurements of the distance between myosin filaments comprising the smectic B1 liquid crystal found in skinned crayfish striated muscle were made. The interfilament distanceas a function of applied compressive osmotic pressure wasdetermined and the bulk modulus of this myofilament liquid crystal ascertained. Under compression the behavior of this myosin filament lattice is shown to be predicted well by the Murnaghan equation of state. The isothermal bulk modulus, B o, of this myosin filament liquid crystal is 1.51 × 105 dynes/cm2 at 2°C and at 46% actin overlap.