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Studies on the Role of Histones in the Structure and Function of Chromatin


Smart, John Edward (1970) Studies on the Role of Histones in the Structure and Function of Chromatin. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/DQN1-VN19.


Studies on the dissociation of histones from chromatin by increasing concentrations of sodium deoxycholate (DOC) have shown that histrone II is removed at lowest concentrations of DOC, while slightly higher concentrations remove histones III and IV. Still higher concentrations remove histone I.

The complete separation of chromatin and 14C-DOC by sucrose sedimentation indicated that the binding of DOC to chromatin is readily and completely reversible.

The dissociation of histones from chromatin by increasing concentrations of related cholanic acids and some of their conjugated derivatives were studied. The results suggested that the driving force for the interaction between the cholanic acid anion and histones is the lowering of the activity coefficient of the cholanic acid anion which occurs when it is partially removed from solution by interaction with hydrophobic regions of the positively charged histones.

The role of histones in the structure of chromatin has been studied by comparing the effects of selective removal of histones from chromatin by increasing concentrations of DOC with those caused by NaCl (removes histone I at lowest concentrations, while higher concentrations remove histones II, III, and IV). Properties studied included thermal denaturation, sedimentation velocity, flow dichroism, relaxation times of molecules oriented in a flow field, and the irreversible disruption of a 130 S, cross-linked component of sheared chromatin. The data indicated that none of the structural or chemical parameters with which these properties are correlated show a dependence on the presence of one particular histone fraction.

The template activity (ability to prime a 0.2 M KC1 DNA-dependent RNA synthesis system catalyzed by E. coli RNA polymerase) increases from that of native chromatin (approximately 25 per cent of that pure DNA) to that of pure DNA in a fashion which shows a nearly linear relationship to the amount of histone coverage of the template. The precipitability of partially dehistonized chromatin samples in 0.15 M NaCl shows a large dependence on the presence of histone I.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:(Biochemistry and Chemistry)
Degree Grantor:California Institute of Technology
Major Option:Biochemistry
Minor Option:Chemistry
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Bonner, James Frederick
Thesis Committee:
  • Unknown, Unknown
Defense Date:15 September 1969
Funding AgencyGrant Number
Public Health ServiceUNSPECIFIED
Record Number:CaltechTHESIS:09032015-162652124
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9138
Deposited On:08 Sep 2015 20:10
Last Modified:21 May 2024 23:52

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