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Bioinorganic Chemistry and Applications
Volume 2007, Article ID 10720, 9 pages
Research Article

NMR Structure and CD Titration with Metal Cations of Human Prion α2-Helix-Related Peptides

1Dipartimento delle Scienze Biologiche, Centro Interuniversitario di Ricerca sui Peptidi Bioattivi, Università Federico II di Napoli e Istituto di Biostrutture e Bioimmagini, CNR, Via Mezzocannone 16, Napoli 80134, Italy
2Dipartimento di Scienze e Tecnologie per l'Ambiente e il Territorio, Università del Molise, Contrada Fonte Lappone, Pesche 86090, Italy
3Istituto di Chimica Biomolecolare, CNR, Via Campi Flegrei 34, Pozzuoli 80078, Italy
4Dipartimento di Biochimica e Biofisica e CRISCEB, Seconda Università di Napoli, Via Santa Maria di Costantinopoli 16, Napoli 80138, Italy

Received 8 March 2007; Revised 4 June 2007; Accepted 11 July 2007

Academic Editor: Ivano Bertini

Copyright © 2007 Luisa Ronga et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The 173–195 segment corresponding to the helix 2 of the C-globular prion protein domain could be one of several “spots” of intrinsic conformational flexibility. In fact, it possesses chameleon conformational behaviour and gathers several disease-associated point mutations. We have performed spectroscopic studies on the wild-type fragment 173–195 and on its D178N mutant dissolved in trifluoroethanol to mimic the in vivo system, both in the presence and in the absence of metal cations. NMR data showed that the structure of the D178N mutant is characterized by two short helices separated by a kink, whereas the wild-type peptide is fully helical. Both peptides retained these structural organizations, as monitored by CD, in the presence of metal cations. NMR spectra were however not in favour of the formation of definite ion-peptide complexes. This agrees with previous evidence that other regions of the prion protein are likely the natural target of metal cation binding.