The interaction of core histones with DNA: equilibrium binding studies.
The binding of core histone proteins to DNA, measured as a function of [NaCl[ is a reversible process. Dissociation and reassociation occurs in two stages. Between 0.7 and 1.2 M NaCl H2a H2b bind non-cooperatively as an equimolar complex with deltaGo = 1.6 Kcals/mole at 4 degree C and 1.0 M NaCl. Between 1.2 and 2.0 M NaCl H3 and H4 bind cooperatively as an equimolar complex with delta Go = 7.4 Kcal/mole at 4 degree C and 1.0 M NaCl. The proper binding of H2a and H2b requires the presence of bound H3 and H4. Nuclease digestion of the H3-H4 DNA produces a tetramer of H3-H4 bound to fragments of DNA 145, 125 and 104 base pairs long. Thus an H3-H4 tetramer can protect fragments of DNA as long as those found in complete core particles and must therefore span the nucleosome core particle.
D000818:Animals; D002417:Cattle; D002474:Cell-Free System; D002843:Chromatin / Q000648:ultrastructure*; D002942:Circular Dichroism; D004247:DNA / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D006657:Histones / Q000378:metabolism*; D008836:Micrococcal Nuclease / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects; D012965:Sodium Chloride / Q000494:pharmacology; D013950:Thymus Gland
D002843:Chromatin; D006657:Histones; D012965:Sodium Chloride; D004247:DNA; D008836:Micrococcal Nuclease