Peculiarities of the amino acid composition, spatial organization and interaction with DNA of histones H1 from calf thymus and carp spermatozoa

The amino acid composition of the H1-like histone isolated from carp spermatozoa (H1carp) is characterized by a high content of lysine (34.6%) and a low content of glycine (4.5%) as compared to that of its calf counterpart (H1calf). The Lys/Arg ratio is 21.6, which is much higher than that for the H1-like histones from other species spermatozoa (cf. echinodermata). It was shown that the fluorescence anisotropy and excitation spectra of histones H1carp and H1calf change synchronically. At the same time the final folding of the polypeptide chains of these histones within their ternary structure is different. These differences manifest themselves in a distinct quantum yield of both histones and different accessibility of the single tyrosine residue for fluorescence quenchers. In histone--DNA complexes the tyrosine fluorescence is quenched. An increase in the ionic strength gives rise to a formation of large-sized aggregates in a histone H1--DNA solution which contain structurally heterogenous histones H1 from different sources. Histone H1carp causes DNA aggregation at lower ionic strength values than its calf counterpart. The complexes are dissociated at 0.6 M NaCl.