High resolution proton magnetic resonance spectroscopy of histones and histone-histone complexes in aqueous solution

Abstract

Low MW [chicken erythrocyte] histone complexes of H2A (.simeq. dimer), H2B ( .simeq. tetramer), H3-H4 ( .simeq. tetramer), H2A-H2B ( .simeq. dimer), and H2B-H4 ( .simeq. dimer) were prepared in 2 M NaCl and neutral pH at 4.degree. C. These materials are free of nonspecific aggregate and are suitable for study by high resolution PMR spectroscopy. Such spectra were recorded in aqueous solution under conditions allowing a study of the exchangeable proton resonances of histone complexes for the first time and indicate that the structured regions are rich in hydrophobic amino acids, as well as arginine and some acidic amino acids. Most of the lysine and probably alanine residues remain in a motile, random coil-like state after formation of the complexes. Arginine residues may be important in inter- and/or intra-subunit interactions in histone complexes.