The conformation of histone f2a1 (histone IV) in solution at low inoic strength

Hydrodynamic studies of histone f2a1 are performed in dilute salt solution. Protein sedimentation is shown to be dependent upon the partial specific volume and molarity of the supporting electrolyte. To compensate for the secondary chage effect, a solvent of dilute tetramethylammonium chloride, for which (1 − V̄saltρ) ≅ 0, is used. To correct for the primary charge effect in sedimentation, a special linear extrapolation to infinte dilution of the protein is employed. Measurements of intrinsic viscosity are interpreted in terms of an increase in molecular dimension with a decrease in ionic strength. The conformation of histone f2a1 in dilute salt solution is interpreted from sedimentation and viscosity data to be that of a highly charged random coil possessing 20–30% of nuclear globular structure.