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Investigations of nonhistone chromosomal proteins


Elgin, Sarah Carlisle Roberts (1972) Investigations of nonhistone chromosomal proteins. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/6VGH-RZ17.


The major nonhistone chromosomal proteins (NHC proteins) are a group of 14-20 acidic proteins associated with DNA in eukaryotic chromatin. In comparisons by SDS gel electrophoresis (molecular weight sieving) one observes a high degree of homology among the NHC protein fractions of different tissues from a given species. Tissue-specific protein bands are also observed. The appearance of a new NHC protein, A, in the NHC proteins of rat liver stimulated to divide by partial hepatectomy and of rat ascites cells suggests that this protein may play a role in preparing the cell for division. The NHC proteins of the same tissue from different species are also very similar. Quantitative but not qualitative changes in the NHC proteins of rat uterus are observed on stimulation (in vivo) with estrogen. These observations suggest that the major NHC proteins play a general role in chromatin structure and the regulation of genome expression; several may be enzymes of nucleic acid and histone metabolism and/or structural proteins analogous to histones. One such enzyme, a protease which readily and preferentially degrades histones, can be extracted from chromatin with 0.7 N NaCl.

Although the NHC proteins readily aggregate, they can be separated from histone and fractionated by ion exchange chromatography on Sephadex SE C-25 resin in 10 M urea-25% formic acid (pH 2.5). Following further purification, four fractions of NHC protein are obtained; two of these are single purified proteins, and the other two contain 4-6 and 4-7 different proteins. These NHC proteins show a ratio of acidic to basic amino acids from 2.7 to 1.2 and isoelectric points from apparently less than 3.7 to 8.0. These isolated fractions appear more soluble and easier to work with than any whole NHC protein preparation.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Biochemistry and Neurophysiology
Degree Grantor:California Institute of Technology
Major Option:Biochemistry
Minor Option:Neurobiology
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Bonner, James Frederick
Thesis Committee:
  • Dreyer, William J.
  • Davidson, Norman R.
Defense Date:15 September 1971
Funding AgencyGrant Number
Record Number:CaltechTHESIS:04182016-080802139
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9674
Deposited On:18 Apr 2016 16:44
Last Modified:09 Nov 2022 19:20

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