title: Studies on the structure of isolated chromatin in three different solvents.
abstract: Properties of calf thymus chromatin, prepared by mild procedures, have been studied in various solvents. In 0.2 mM EDTA s-values ranged from 20 to 30 S and intrinsic viscosities from 5 to 24 dl/g. Dialysis against 0.15 M NaCl or 0.2 mM MgCl2 changed these values to 80 to 100 S and 0.2 to 5 dl/g, respectively, indicating an essentially more compact structure. In 0.2 mM EDTA X-ray scattering yielded a cross section diameter of 9 nm, which is associated with the tertiary structure of chromatin fiber (M/L = 21200 Dalton/nm). By dialysis against 0.15 M NaCl or 0.2 mM MgCl2 part of the material spontaneously formed quarterny structures (cross section diameters 25-29 nm). The rest of the material with cross section diameters less than 9 nm is supposed to be more strongly sheared tertiary structure which seems to be unable to form quarterny structure due to artificial conformational changes.
mesh_terms: D000818:Animals; D002417:Cattle; D002458:Cell Fractionation / Q000379:methods; D002843:Chromatin / Q000648:ultrastructure*; D004247:DNA / Q000032:analysis; D009690:Nucleic Acid Conformation; D012997:Solvents; D013950:Thymus Gland / Q000648:ultrastructure; D014783:Viscosity; D014961:X-Ray Diffraction
chemical_list: D002843:Chromatin; D012997:Solvents; D004247:DNA