LAUSR

Abstract The interaction of Cu(II) ions with the peptide Ac-GYDVEK-amide (N and C-terminal protected), a well conserved sequence located at N-terminal of the globular domain of somatic histone H1 variants (H1.1–H1.5) was studied by means of potentiometry and spectroscopic techniques. In the absence of a histidine residue, the β-COOH of the aspartic acid becomes the primary binding site. Curiously, this weak binding can prevent Cu(II) precipitation and promote the ionization and coordination of the next two amide donors, although at higher pH values compared to typical N-type anchors. The concentration of the complex formed at physiological pH with a {2N, 2O} donor set is high and accounts for almost 85% of the total Cu(II) ion concentration. The above observation provides an indirect proof of its enhanced thermodynamic stability. Efficient copper binding with this part of the globular domain might have a negative impact in both compacting and DNA regulatory roles of the histone H1.