Spectroscopic studies on metal complexes of Aspergillus awamori-derived recombinant human lactoferrin

The interaction of Fe(III) and Cu(II) with Aspergillus awamori-derived reco mbinant human lactoferrin was studied by means of UV-Vis and electron param agnetic resonance spectroscopy. Results are interpreted as to indicate that non-specific metal binding occurs after a 2:1 stoichiometric metal uptake at the two specific binding sites of lactoferrin has taken place. Like wild -type lactoferrin from human milk, the expressed protein also coordinates t he metal at the two specific binding sites to two deprotonated tyrosil and one histidine side chain, one aspartate and a bidentate sinergistic anion, here carbonate. Results of the cobalt(III), manganese(III), cerium(III) and cerium(IV) lactoferrin complexes are also presented and differences induce d by the medium (Tris-HCl, phosphate and Hepes buffers) are explained. (C) 2000 Elsevier Science S.A. All rights reserved.