Dimensions of Xf virus from its rotational and translational diffusion coefficients

Measurements on monodisperse preparations of the filamentous virus Xf give 17.3 +/- 0.6 s-1 for its rotational diffusion coefficient in 1 mM sodium phosphate, pH 7.5 at 20 degrees C and (2.53 +/- 0.06) X 10(-8) cm2 s-1 for its translational diffusion coefficient in 0.15 M NaCl and 0.015 M sodium phosphate, pH 7, at 25 degrees C. These coefficients yield a length of 980 +/- 30 nm and a diameter of 7.2 +/- 1.5 nm for the virus in solution when used to solve simultaneously the two Broersma equations for the diffusion of rigid rods.