The effect of rotor velocity on sedimentation coefficients.

Sedimentation-coefficient measurements on human IgG, fibrinogen and alpha(2)-macroglobulin and pig thyroglobulin were made at rotor velocities of 15220-59780 rev./min and 25.0 degrees C in capillary-type synthetic-boundary cells or ordinary cells. At the lowest velocity, IgG and fibrinogen gave results several per cent higher than at other velocities, whereas alpha(2)-macroglobulin and thyroglobulin gave values only about 1.5% higher. This behaviour of IgG and fibrinogen is attributed primarily to imperfect initial boundaries.