Studies on deoxyribonucleoprotein structure. Sedimentation behaviour

The sedimentation behaviour of DNP samples from calf thymus partially depleted of protein was studied. Upon transition from DNP to DNA a twofold decrease of the sedimentation constant, S02 0,W was observed. The translational friction coefficient f of DNP calculated from S02 0,W does not change at deproteinization, whereas the intrinsic viscosity [η] increases notably. Such difference in the dependence of f and [η] on the protein content is interpreted in terms of the theories for semirigid coils. The application of different models of DNP structure for the description of the hydrodynamic behaviour of DNP is considered. A model of the semirigid coil formed by a DNP chain partly folded into the superhelix seems to be most preferable.