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Copper and nickel binding in multi-histidinic peptide fragments

Zoroddu, Maria Antonietta and Medici, Serenella and Peana, Massimiliano Francesco (2009) Copper and nickel binding in multi-histidinic peptide fragments. Journal of Inorganic Biochemistry, Vol. 103 (9), p. 1214-1220. ISSN 0162-0134. Article.

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DOI: 10.1016/j.jinorgbio.2009.06.008

Abstract

Multi-histidinic peptides have been investigated for Cu(II) and Ni(II) binding. We present spectroscopic evidence that, at low pH and from sub-stoichiometric to stoichiometric amounts of metals, macrochelate and multi-histidinic Cu(II) and Ni(II) complexes form; but, from neutral pH and above, both copper and nickel bind to individual histidine residues. NMR, EPR, UV–Visible (UV–Vis) and UV–Visible CD spectroscopy were used to understand about the variety of complexes obtained at low pHs, where amide deprotonation and coordination is unfavoured. A structural transition between two coordination geometries, as the pH is raised, was observed. Metal binds to Nδ of histidine imidazole when main-chain coordination is involved and coordinates via Nε under mildly acidic conditions and sub-stoichiometric amounts of metals. From EPR results a distortion from planarity has been evidenced for the Cu(II) multi-histidinic macrochelate systems, which may be relevant to biological activity. The behaviour of our peptides was comparable to the pH dependent effect on Cu(II) coordination observed in octapeptide repeat domain in prion proteins and in amyloid precursor peptides involved in Alzheimer’s disease. Changes in pH and levels of metal affect coordination mode and can have implications for the affinity, folding and redox properties of proteins and peptide fragments.

Item Type:Article
ID Code:3504
Status:Published
Refereed:Yes
Uncontrolled Keywords:Multi-histidinic peptides, Cu (II), Ni (II), NMR, EPR, CD
Subjects:Area 03 - Scienze chimiche > CHIM/03 Chimica generale e inorganica
Divisions:001 Università di Sassari > 01 Dipartimenti > Chimica
Publisher:Elsevier
ISSN:0162-0134
Deposited On:22 Jan 2010 12:58

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