Selective dissociation of histones from calf thymus nucleoprotein

Heiko H. Ohlenbusch, Baldomero M. Olivera, Dorothy Tuan Lo, Norman Davidson

Research output: Contribution to journalArticle

262 Citations (Scopus)

Abstract

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.

Original languageEnglish (US)
JournalJournal of Molecular Biology
Volume25
Issue number2
StatePublished - Apr 28 1967
Externally publishedYes

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Nucleoproteins
Histones
Thymus Gland
Salts
DNA
Sodium Chloride
Freezing
Electrophoresis
Gels
Static Electricity
Centrifugation
Chromatography

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology

Cite this

Ohlenbusch, H. H., Olivera, B. M., Tuan Lo, D., & Davidson, N. (1967). Selective dissociation of histones from calf thymus nucleoprotein. Journal of Molecular Biology, 25(2).

Selective dissociation of histones from calf thymus nucleoprotein. / Ohlenbusch, Heiko H.; Olivera, Baldomero M.; Tuan Lo, Dorothy; Davidson, Norman.

In: Journal of Molecular Biology, Vol. 25, No. 2, 28.04.1967.

Research output: Contribution to journalArticle

Ohlenbusch, HH, Olivera, BM, Tuan Lo, D & Davidson, N 1967, 'Selective dissociation of histones from calf thymus nucleoprotein', Journal of Molecular Biology, vol. 25, no. 2.
Ohlenbusch HH, Olivera BM, Tuan Lo D, Davidson N. Selective dissociation of histones from calf thymus nucleoprotein. Journal of Molecular Biology. 1967 Apr 28;25(2).
Ohlenbusch, Heiko H. ; Olivera, Baldomero M. ; Tuan Lo, Dorothy ; Davidson, Norman. / Selective dissociation of histones from calf thymus nucleoprotein. In: Journal of Molecular Biology. 1967 ; Vol. 25, No. 2.
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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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