Di Natale, Giuseppe and Grasso, Giulia and Impellizzeri, Giuseppe and La Mendola, Diego and Micera, Giovanni and Mihala, Nikolett and Nagy, Zoltán and Osz, Katalin and Pappalardo, Giuseppe and Rigó, Viktória and Rizzarelli, Enrico and Sanna, Daniele and Sóvágó, Imre (2005) Copper(II) interaction with unstructured prion domain outside the octarepeat region: speciation, stability, and binding details of copper(II) complexes with prp106-126 peptides. Inorganic Chemistry, Vol. 44 (20), p. 7214-7225. eISSN 1520-510X. Article.
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Copper(II) complexes of the neurotoxic peptide fragments of human and chicken prion proteins were studied by potentiometric, UV−vis, CD, and EPR spectroscopic and ESI-MS methods. The peptides included the terminally blocked native and scrambled sequences of HuPrP106−126 (HuPrPAc106−126NH2 and ScrHuPrPAc106−126NH2) and also the nona- and tetrapeptide fragments of both the human and chicken prion proteins (HuPrPAc106−114NH2, ChPrPAc119−127NH2, HuPrPAc109−112NH2, and ChPrPAc122−125NH2). The histidyl imidazole-N donor atoms were found to be the major copper(II) binding sites of all peptides; 3N and 4N complexes containing additional 2 and 3 deprotonated amide-N donors, respectively, are the major species in the physiological pH range. The complex formation processes for nona- and tetrapeptides are very similar, supporting the fact that successive deprotonation and metal ion coordination of amide functions go toward the N-termini in the form of joined six- and five-membered chelates. As a consequence, the peptide sequences investigated here, related to the neurotoxic region of the human PrP106−126 sequence, show a higher metal-binding affinity than the octarepeat fragments. In the case of the HuPrP peptide sequences, a weak pH-dependent binding of the Met109 residue was also detected in the 3N-coordinated complexes.
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