title: Conformational studies on histone H3 and its CNBr peptides.
abstract: Histone H3 and H3 peptides 1--120, 1-90, 91-135, 91-120 and 121-135 have been prepared and examined for salt-induced conformational changes by circular dichroism measurements. It was found that reduced histone H3 and the reduced peptides 1-120, 91-135 and 91-120 exhibit biphasic changes with the formation of alpha-helix and beta structures. H3 peptide 1-90, on increasing the ionic strength to moderately high levels, monophasically formed appreciable quantities of alpha-helix and beta structures, while peptide 121-135 remained unfolded under all ionic strengths examined. All the above peptides except 121-135 also aggregate when the ionic strength is raised. The salt-induced near-ultraviolet circular dichroic spectra of histone H3 and peptide 1-90 were found to be very similar, suggesting that the conformational changes induced in the peptide 1-90 are essentially the same as those observed for the intact histone. These results support the contention that the polypeptide segments of this histone interact initially by parallel self-association followed by the formation of even larger aggregates on a longer scale.
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002417:Cattle; D002942:Circular Dichroism; D003488:Cyanogen Bromide; D006657:Histones; D046911:Macromolecular Substances; D010446:Peptide Fragments; D011487:Protein Conformation; D013056:Spectrophotometry, Ultraviolet; D013950:Thymus Gland
chemical_list: D000596:Amino Acids; D006657:Histones; D046911:Macromolecular Substances; D010446:Peptide Fragments; D003488:Cyanogen Bromide