Nucleic Acids Research, 1979, Vol. 6, No. 5 2017-2027
© 1979
Articles |
Studies on the structure of isolated chromatin in three different solvents
Institut für Medizinische Molekularbiologie, Medizinische Hochschule Lubeck D2400 Uüeck, GFR
Received December 5, 1978. 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 MgC12 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 <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.