Intrinsic and extrinsic fluorescence of histones H2A and H2B: a conformational study.

Intrinsic and extrinsic fluorescence measurements suggest that H2A and H2B histones, in a partially secondary structure, self-aggregate into assemblies in which some tyrosine groups are buried in a hydrophobic environment and show enhanced fluorescence, 2-p-toluidinylnaphthalene-6-sulfonate (TNS) indicates heterogeneity among the binding sites whose number depends on the pH values of the solutions. Warfarin, used as hydrophobic probe, shows that during the process of self-association and cross-complexing of the two histones there is the covering of some hydrophobic sites of the proteins.