Effect of non-histone proteins on thermal transition of chromatin and of DNA.
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.
D000818:Animals; D002467:Cell Nucleus / Q000648:ultrastructure; D055598:Chemical Phenomena; D002621:Chemistry; D002843:Chromatin / Q000302:isolation & purification; D002868:Chromosomal Proteins, Non-Histone / Q000302:isolation & purification; D004247:DNA; D004355:Drug Stability; D006493:Heparin; D008099:Liver / Q000032:analysis; D046911:Macromolecular Substances; D008970:Molecular Weight; D009691:Nucleic Acid Denaturation; D011489:Protein Denaturation; D051381:Rats; D013696:Temperature; D014508:Urea
D002843:Chromatin; D002868:Chromosomal Proteins, Non-Histone; D046911:Macromolecular Substances; D014508:Urea; D006493:Heparin; D004247:DNA