Defer N, Kitzis A, Kruh J, Brahms S, Brahms J. Effect of non-histone proteins on thermal transition of chromatin and of DNA.
Nucleic Acids Res 1977;
4:2293-306. [PMID:
909776 PMCID:
PMC342567 DOI:
10.1093/nar/4.7.2293]
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Abstract
The effect of chromatin non-histone protein on DNA and chromatin stability is investigated by differential thermal denaturation method. 1) Chromatin (rat liver) yields a multiphasic melting profile. The major part of the melting curve of this chromatin is situated at temperatures higher than pure DNA, with a distinct contribution due to nucleosomes melting. A minor part melts at temperatures lower than DNA which may be assigned to chromatin non-histone protein-DNA complex which destabilized DNA structure. 2) Heparin which extracts histones lowers the melting profile of chromatin and one observes also a contribution with a Tm lower that of pure DNA. In contrast, extraction on non-histone proteins by urea supresses the low Tm peak. 3) Reconstitution of chromatin non-histone protein-DNA complexes confirms the existence of a fraction of chromatin non-histone protein which lowers the melting temperature when compared to pure DNA. It is concluded that chromatin non-histone proteins contain different fractions of proteins which are causing stabilizing and destabilizing effect on DNA structure.
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