[Conformational peculiarity of H1 histones of calf thymus and sea urchin sperm].

The secondary structure, sizes and form of H1 histone molecules of calf thymus (H1-T) and sea urchin sperm (H1-S) were studied by circular dichroism, sedimentation and diffusion. An increase in the ionic strength of solution is shown to result in the formation of alpha-helical parts in H1-T and both alpha-helical and beta-structural parts of H1-S. An analysis of amino acid composition of histones and their compaction under these conditions enables a conclusion that the resulting B-structure is antiparallel and intramolecular. The above properties of H1-S can result in a more dense compactness of the sea urchin sperm chromatin.