Study of conformational states and reversibility of histone complexes.
The core histone complex (H3:H4:H2A:H2B)2 and products of dissociation, the H2A:H2B: dimer and the H3:H4 tetramer, were isolated from chicken erythrocyte chromatin by several literature methods as well as gel filtration on Bio-Gel A15m at various salt concentrations. The conformational and oligomeric characteristic of these histone complexes were compared to analogous histone complexes prepared by renaturation of individually acid-extracted histones by circular dichroism (CD) and analytical gel filtration chromatography. The salt-extracted core histone complex (independent of method of preparation), the purified dissociation products, the H2A:H2B dimer, and the H3:H4 tetramer in 2 M NaCl, 10 mM sodium phosphate, 0.25 mM EDTA and 0.1 mM DTT, pH 7.0, have conformation which are identical, by the criteria of similar CD spectra, with complexes prepared from acid-extracted histones, Likewise, the salt-extracted complexes may be cycled through solvents of low ionic strength (10 mM sodium phosphate, pH 7.0 or 50 mM NaOAc, pH 5.0) or 1 mM HCl and returned to 2.0 M NaCl, 10 mM sodium phosphate, 0.25 mM EDTA, and 0.1 mM DTT, pH 7.0, in a completely reversible manner. Thus it would appear that acid-denatured histones are capable of being fully renatured to yield native-like complexes.
D000818:Animals; D002467:Cell Nucleus / Q000032:analysis; D002645:Chickens; D002942:Circular Dichroism; D004229:Dithiothreitol; D004912:Erythrocytes / Q000032:analysis; D006657:Histones / Q000097:blood / Q000302:isolation & purification; D046911:Macromolecular Substances; D008970:Molecular Weight; D011487:Protein Conformation; D013056:Spectrophotometry, Ultraviolet
D006657:Histones; D046911:Macromolecular Substances; D004229:Dithiothreitol