title: Studies on histone organization in the nucleosome using formaldehyde as a reversible cross-linking agent.
abstract: A new procedure is described which allows selective reversal of formaldehyde cross-linking in both histone-histone and histone-DNA of nuclei isolated from calf thymus. All ten possible dimers of the four non-H1 histones, H3, H2B, H2A and H4, are observed, the major dimers being H3-H3, H3-H2A, H2B-H2A, H2a-H2A and two separate dimers of H2B-H4. Although oligomers of the non-H1 histones are formed by prolonged treatment with this reagent, 50% of the histones continue to remain resistant to cross-linking with each other. For those histones which cross-linking with each other. For those histones which cross-link, the site of cross-linking within the molecules is located in the "core" (trysin-resistant) regionand therfore indicates proximities for these molecules within the nucleosome. The core region also cross-links to DNA, indicating intimate interactions between this region in all the non-H1 histones with DNA.
mesh_terms: D001665:Binding Sites; D055598:Chemical Phenomena; D002621:Chemistry; D002843:Chromatin / Q000648:ultrastructure*; D004247:DNA / Q000378:metabolism*; D005557:Formaldehyde; D006657:Histones / Q000378:metabolism*; D046911:Macromolecular Substances; D008722:Methods; D008970:Molecular Weight; D011485:Protein Binding
chemical_list: D002843:Chromatin; D006657:Histones; D046911:Macromolecular Substances; D005557:Formaldehyde; D004247:DNA