The influence of primary structure changes on the higher order structure of histone H2B

Structural changes of histones H2B in aqueous media were studied under conditions of varying pH and ionic strength. The techniques involved intrinsic fluorescence of tyrosine residues, extrinsic fluorescence using the hydrophobic probe 8-anilinonaphthalene sulfonate and fluorescence polarization. Secondary structure predictive methods were also used to study potential effects of primary mutations. In spite of many primary structure changes, the predicted effect on a globular structure of H2B is minimal. The results indicate the formation of a major hydrophobic region, the formation of helices and the burial of tyrosine residue 83 (calf), the structural changes of which appear to be identical in all H2B's as ionic strength is increased. The effect of primary structure changes on protein-protein interaction where H2B's are concerned is likely to be negligible, whereas the major effect is likely to be the protein-DNA interaction where H2B could be at least partially responsible for differentiation.