Copper(II) complexes of prion protein PEG11-tetraoctarepeat fragment: spectroscopic and voltammetric studies

Spectroscopic (UV-Vis and EPR) and voltammetric studies have been carried out on the copper(II) complexes with the Ac-PEG11-(PHGGGWGQ)4-NH2 (L) polypeptide. In the ratios Cu : L 3 : 1 and 4 : 1, the two [Cu3(L)H(-6)] and [Cu4(L)H(-8)] complex species have been characterized at neutral pH values. All...

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Published in:Dalton transactions : an international journal of inorganic chemistry 2009-04 (14), p.2637-2646
Main Authors: Bonomo, Raffaele P, Di Natale, Giuseppe, Rizzarelli, Enrico, Tabbì, Giovanni, Vagliasindi, Laura I
Format: Article
Language:English
Subjects:
Copper - chemistry
Electrochemistry
Electrodes
Electron Spin Resonance Spectroscopy
Ligands
Nitric Oxide - chemistry
Organometallic Compounds - chemistry
Peptides - chemistry
Prions - chemistry
Spectrophotometry, Ultraviolet
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Summary:Spectroscopic (UV-Vis and EPR) and voltammetric studies have been carried out on the copper(II) complexes with the Ac-PEG11-(PHGGGWGQ)4-NH2 (L) polypeptide. In the ratios Cu : L 3 : 1 and 4 : 1, the two [Cu3(L)H(-6)] and [Cu4(L)H(-8)] complex species have been characterized at neutral pH values. All the copper atoms occupy similar coordination sites formed by imidazole, peptidic nitrogen atoms and carbonyl oxygen atoms in a square base pyramidal geometry. Voltammetric measurements on these systems point out the cooperativity in the electron transfer processes among the copper(II) sites during their reduction. NO interaction with these polynuclear copper species is characterized by the reduction of the copper sites through the formation of two different intermediate complex species. When an excess of the Ac-PEG11-(PHGGGWGQ)4-NH2 ligand is considered, frozen solution EPR parameters and UV-Vis spectroscopic data identify the [Cu(N(im))4]2+ chromophore, which does not interact with NO.
ISSN:1477-9226
1477-9234
DOI:10.1039/b821727k