Tightly Bound Non‐histone Proteins in Nucleosomes from Pig‐Liver Chromatin

• Published in: European journal of biochemistry Vol. 121; no. 1; pp. 15 - 19
• Main Authors: CAIAFA, Paola, SCARPATI‐CIOFFARI, M. Rosaria, ALTIERI, Fabio, ALLEGRA, Paola, LONIGRO, Renata, TURANO, Carlo
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.12.1981
• Subjects: Animals; Chromosomal Proteins, Non-Histone - isolation & purification; Chromosomal Proteins, Non-Histone - metabolism; DNA - metabolism; Guanidine; Guanidines; Hydroxyapatites; Liver - metabolism; Micrococcal Nuclease; Molecular Weight; Nucleosomes - metabolism; Swine; Urea
• ISSN: 0014-2956; 1432-1033
• DOI: 10.1111/j.1432-1033.1981.tb06422.x

Core particles prepared by micrococcal nuclease digestion of pig liver chromatin have been adsorbed on hydroxyapatite and dissociated by gradual increase in ionic strength and finally by urea and guanidine. By this method non‐histone proteins have been found to be associated with the core particles. Proteins tightly bound to the core particle DNA (i.e. dissociated only by urea and guanidine) have also been found: these are proteins with a limited heterogeneity, with respect to their molecular weights, since only six components are present with molecular weights ranging from 71 000 to 20000. They show, furthermore, a peculiar amino acid composition. Other tightly bound proteins have been shown to be present only in the spacer regions. The existence of two differ‐ ent classes of tightly bound proteins probably reflects different modes of binding to the DNA, which are com‐ patible or incompatible, respectively, with the simultaneous binding of the histone octamer.