TY - JOUR
T1 - Selective dissociation of histones from calf thymus nucleoprotein
AU - Ohlenbusch, Heiko H.
AU - Olivera, Baldomero M.
AU - Tuan, Dorothy
AU - Davidson, Norman
N1 - Funding Information:
Without the generous advice and help of Professors J. Bonner and R. C. Huang, this work would have been quite impossible. Mr D. Fambrough has generously contributed essential advice and help. The research has been supported by grants GM 10991 and GM 13762 from the United States Public Health Service. One of us (B. M. 0.) is grateful to the U.S. Educational Foundation in the Phillipines for a fellowship.
PY - 1967/4/28
Y1 - 1967/4/28
N2 - The extent of the dissociation of histones from nucleohistone by increasing concentrations of sodium chloride and sodium perchlorate has been measured. Dissociated histones were separated from nucleohistone in a given salt medium by differential centrifugation. The histone fractions were identified by gel electrophoresis, or, in some preliminary experiments, by column chromatography. Histone fraction I is dissociated from nucleohistone by NaCl in the range of 0.4 to 0.5 m. Histone II is dissociated by 0.8 to 1.2 m-NaCl. Histone III-IV consists of two components B1 and A, by gel electrophoresis. The B1 component is dissociated from native nucleohistone in the range 0.8 to 1.2 m-NaCl, the A component in the range 0.9 to 1.6 m. The NaClO4 studies are not as detailed, but the general result is that the concentration of NaClO4 needed to dissociate a certain histone fraction is about half the concentration of NaCl needed. The dissociation of a histone fraction is somewhat co-operative and takes place over a rather small salt concentration range. These results imply that both electrostatic and non-electrostatic interactions contribute to the strength of the binding between histones and DNA. The results of the sedimentation separations were confirmed by electrophoretic separations in different salt concentrations. Furthermore, and as expected, the more histone dissociated from a nucleohistone, the greater the electrophoretic velocity of the latter. The optical melting profiles of partially dissociated nucleohistones in a medium of low salt concentration are intermediate between those of fully covered nucleohistone and DNA. The melting curves for the partially covered materials are broader than those for fully covered nucleohistone or for DNA, but not clearly biphasic. The results therefore suggest that the histones are somewhat heterogeneously distributed along the DNA chain. Fully covered native nucleohistone is insoluble at sodium chloride concentrations in the range 0.15 to 0.30 m. Nucleohistone, from which histone I has been removed by extraction with 0.6 m-NaCl, is soluble in 0.15 to 0.30 m-NaCl.
AB - The extent of the dissociation of histones from nucleohistone by increasing concentrations of sodium chloride and sodium perchlorate has been measured. Dissociated histones were separated from nucleohistone in a given salt medium by differential centrifugation. The histone fractions were identified by gel electrophoresis, or, in some preliminary experiments, by column chromatography. Histone fraction I is dissociated from nucleohistone by NaCl in the range of 0.4 to 0.5 m. Histone II is dissociated by 0.8 to 1.2 m-NaCl. Histone III-IV consists of two components B1 and A, by gel electrophoresis. The B1 component is dissociated from native nucleohistone in the range 0.8 to 1.2 m-NaCl, the A component in the range 0.9 to 1.6 m. The NaClO4 studies are not as detailed, but the general result is that the concentration of NaClO4 needed to dissociate a certain histone fraction is about half the concentration of NaCl needed. The dissociation of a histone fraction is somewhat co-operative and takes place over a rather small salt concentration range. These results imply that both electrostatic and non-electrostatic interactions contribute to the strength of the binding between histones and DNA. The results of the sedimentation separations were confirmed by electrophoretic separations in different salt concentrations. Furthermore, and as expected, the more histone dissociated from a nucleohistone, the greater the electrophoretic velocity of the latter. The optical melting profiles of partially dissociated nucleohistones in a medium of low salt concentration are intermediate between those of fully covered nucleohistone and DNA. The melting curves for the partially covered materials are broader than those for fully covered nucleohistone or for DNA, but not clearly biphasic. The results therefore suggest that the histones are somewhat heterogeneously distributed along the DNA chain. Fully covered native nucleohistone is insoluble at sodium chloride concentrations in the range 0.15 to 0.30 m. Nucleohistone, from which histone I has been removed by extraction with 0.6 m-NaCl, is soluble in 0.15 to 0.30 m-NaCl.
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U2 - 10.1016/0022-2836(67)90143-x
DO - 10.1016/0022-2836(67)90143-x
M3 - Article
C2 - 4291873
AN - SCOPUS:0014219392
SN - 0022-2836
VL - 25
SP - 299-302,IN20,303-315
JO - Journal of Molecular Biology
JF - Journal of Molecular Biology
IS - 2
ER -