Identification of a novel high affinity copper binding site in the APP(145-155) fragment of amyloid precursor protein.
The copper(II) binding features of the APP(145-155) and APP(145-157) fragments of the amyloid precursor protein, Ac-Glu-Thr-His-Leu-His-Trp-His-Thr-Val-Ala-Lys-NH2 and Ac-Glu-Thr-His-Leu-His-Trp-His-Thr-Val-Ala-Lys-Glu-Thr-NH2 were studied by NMR spectroscopy and NMR findings were supported by UV-vis, CD and EPR spectra. Potentiometric measurements were performed only for the more soluble Ac-Glu-Thr-His-Leu-His-Trp-His-Thr-Val-Ala-Lys-Glu-Thr-NH2 peptide fragment. The following was shown: (i) the imidazole rings of all the three His residues are involved in metal coordination; (ii) metal binding induces ionisation of Leu-148 and His-149 amide nitrogens that complete the donor set to copper(II) in the species dominant at neutral pH; (iii) the unusual coordination scheme of the His-Xxx-His-Xxx-His consensus sequence justifies the high specificity for Cu(II) when compared to SOD-like or albumin-like peptides or even in amyloid Abeta fragments. The present findings may represent the key for interpreting the observed requirement of His residues conservation for the redox cycling between Cu(II) and Cu(I) by soluble APP.
Valensin
Daniela
D
Department of Chemistry and the NMR Center, University of Siena, via Moro, 53100 Siena, Italy. valensin@unisi.it
Mancini
Francesca Maria
FM
Łuczkowski
Marek
M
Janicka
Anna
A
Wisniewska
Kornelia
K
Gaggelli
Elena
E
Valensin
Gianni
G
Łankiewicz
Leszek
L
Kozlowski
Henryk
H
D016564:Amyloid beta-Protein Precursor / Q000737:chemistry*; D001665:Binding Sites; D003300:Copper / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular; D010446:Peptide Fragments / Q000737:chemistry; D011487:Protein Conformation
D016564:Amyloid beta-Protein Precursor; D010446:Peptide Fragments; D003300:Copper