NR ABMC
AU Bonomo,R.P.; Imperllizzeri,G.; Pappalardo,G.; Rizzarelli,E.; Tabbi,G.
TI Copper(II) binding modes in the prion octapeptide PHGGGWGQ: a spectroscopic and voltammetric study.
QU Chemistry (Weinheim an der Bergstrasse, Germany) 2000 Nov 17; 6(22): 4195-202
PT journal article
AB The N-terminal octapeptide repeat region of human prion protein (PrPc) is known to bind Cu(II). To investigate the binding modes of copper in PrPc, an octapeptide Ac-PHGGGWGQ-NH2 (1), which corresponds to an octa-repeat sequence, and a tetrapeptide Ac-HGGG-NH2 (2) have been synthesised. The copper(II) complexes formed with 1 and 2 have been studied by circular dichroism (CD) and electron spin resonance (ESR) spectroscopy. Both peptides form 1:1 complexes with Cu(II) at neutral and basic pH. CD, ESR and visible absorption spectra suggest a similar co-ordination sphere of the metal ion in both peptides, which at neutral pH consists of a square pyramidal geometry with three peptidic nitrogens and the imidazole nitrogen as donor atoms. Cyclic voltammetric measurements were used to confirm the geometrical features of these copper(II) complexes: the observation of negative redox potentials are in good agreement with the inferred geometry. All these results taken together suggest that peptide 1 provides a single metal binding site to which copper(II) binds strongly at neutral and basic pH and that the binding of the metal induces the formation of a stiffened structure in the HGGG peptide fragment.
MH Amino Acid Sequence; Circular Dichroism; Copper/*chemistry; Electrochemistry; Electron Spin Resonance Spectroscopy; Human; Molecular Structure; Oligopeptides/*chemistry; Prions/*chemistry; Support, Non-U.S. Gov't
AD Dipartimento di Scienze Chimiche, Universita di Catania, Italy. rbonomo@dipchi.unict.it
SP englisch
PO Deutschland