Histones and DNA methylation in mammalian chromatin. II. Presence of non-inhibitory tightly-bound histones

Biochim Biophys Acta. 1991 Dec 2;1129(1):43-8. doi: 10.1016/0167-4781(91)90210-d.


After removal, by high-salt extraction, of the loosely-bound components present in human placenta chromatin, tightly-bound cationic proteins could be solubilized, by acid extraction, from the 'stripped' chromatin, as well as from the 'stripped' loops or from the 'digested matrix'. These acid-soluble tightly-bound proteins are, in terms of apparent molecular mass and immunoreactivity, quite similar to the 'typical', loosely-bound histones, and, similarly to their 'loosely-bound' counterparts, they can be subdivided in distinct H1-, H2A-, H2B-, H3- and H4-like components, the 'digested matrix' being however characterized by the absence of tightly-bound H1. These tightly-bound histones, at variance from the 'typical' ones, readily find a right-handed helical conformation upon renaturation by progressive dialyses. The H1 components strongly differ also in their effects on enzymic DNA methylation: while 'typical' H1 has a strong inhibitory effect, its tightly-bound counterpart exerts a slight but definite stimulation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Chromatin / chemistry
  • Chromatin / metabolism*
  • Circular Dichroism
  • DNA Modification Methylases / metabolism*
  • Histones / chemistry
  • Histones / isolation & purification
  • Histones / metabolism*
  • Humans
  • Methylation
  • Nucleic Acid Conformation
  • Spectrophotometry, Ultraviolet


  • Chromatin
  • Histones
  • DNA Modification Methylases