Copper and zinc binding properties of the N-terminal histidine-rich sequence of Haemophilus ducreyi Cu,Zn superoxide dismutase.

The Cu,Zn superoxide dismutase (Cu,ZnSOD) isolated from Haemophilus ducreyi possesses a His-rich N-terminal metal binding domain, which has been previously proposed to play a copper(II) chaperoning role. To analyze the metal binding ability and selectivity of the histidine-rich domain we have carried out thermodynamic and solution structural analysis of the copper(II) and zinc(II) complexes of a peptide corresponding to the first 11 amino acids of the enzyme (H(2)N-HGDHMHNHDTK-OH, L). This peptide has highly versatile metal binding ability and provides one and three high affinity binding sites for zinc(II) and copper(II), respectively.

Iron(III)- and copper(II) complexes of an asymmetric, pentadentate salen-like ligand bearing a pendant carboxylate group.

The equilibrium and solution structural properties of the iron(III) and copper(II) complexes of an asymmetric salen-like ligand (N,N'-bis(2-hydroxybenzyl)-2,3-diamino-propionic acid, H(3)bhbdpa) bearing a pendant carboxylate group were characterized in aqueous solution by potentiometric, pH-dependent electron paramagnetic resonance (EPR) and UV-Vis (UV-Visible) measurements. In the equimolar systems the pentadentate ligand forms very stable, differently protonated mononuclear complexes with both metal ions. In the presence of iron(III) {NH, PhO(-), COO(-)}, {2NH, 2PhO(-), COO(-)} and {2NH, 2PhO(-), COO(-), OH(-)} coordinated complexes are dominant.

Reinvestigation of the copper(II)-carcinine equilibrium system: "two-dimensional" EPR simulation and NMR relaxation studies for determining the formation constants and coordination modes.

The equilibria and solution structure of complexes formed between copper(II) and carcinine (beta-alanyl-histamine) at 2< or = pH< or =11.2 have been studied by EPR and NMR relaxation methods. Beside the species that have already been described in the literature from pH-potentiometric measurements, several new complexes have been identified and/or structurally characterized.