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Issue 5, 2009
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Copper(II) coordination outside the tandem repeat region of an unstructured domain of chicken prion protein

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Abstract

Combined potentiometric, calorimetric and spectroscopic methods were used to investigate the Cu2+ binding ability and coordination behaviour of some peptide fragments related to the neurotoxic region of chicken Prion Protein. The systems studied were the following protein fragments: chPrP106–114, chPrP119–126, chPrP108–127, chPrP105–127 and chPrP105–133.

The complex formation always starts around pH 4 with the coordination of an imidazole nitrogen, followed by the deprotonation and binding of amide nitrogens from the peptidic backbone. At neutral pH, the {Nim, 3N} binding mode is the preferred one. The amide nitrogens participating in the binding to the Cu2+ ion derive from residues from the N-terminus side, with the formation of a six-membered chelate ring with the imidazolic side chain.

Comparison of thermodynamic data for the two histydyl binding domains (around His-110 and His-124), clearly indicates that the closest to the hexarepeat domain (His-110) has the highest ability to bind Cu2+ ions, although both of them have the same coordination mode. Conversely, in the case of the human neurotoxic peptide region, between the two binding sites, located at His-96 and His-111, the farthest from the tandem repeat region is the strongest one. Finally, thermodynamic data show that chicken peptide is a distinctly better ligand for coordination of copper ions with respect to the human fragment.

Graphical abstract: Copper(ii) coordination outside the tandem repeat region of an unstructured domain of chicken prion protein

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Publication details

The article was received on 18 Nov 2008, accepted on 09 Feb 2009 and first published on 19 Mar 2009


Article type: Paper
DOI: 10.1039/B820635J
Citation: Mol. BioSyst., 2009,5, 497-510
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    Copper(II) coordination outside the tandem repeat region of an unstructured domain of chicken prion protein

    E. Gralka, D. Valensin, K. Gajda, D. Bacco, Ł. Szyrwiel, M. Remelli, G. Valensin, W. Kamasz, W. Baranska-Rybak and H. Kozłowski, Mol. BioSyst., 2009, 5, 497
    DOI: 10.1039/B820635J

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