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Coordination abilities of mono and multi-histidinic and glutamate peptide fragments towards manganese(II) and cobalt(II)

Zoroddu, Maria Antonietta and Peana, Massimiliano Francesco and Medici, Serenella and Solinas, Costantino and Juliano, Claudia Clelia Assunta and Anedda, Roberto and Nurchi, Valeria Marina and Crisponi, Guido (2012) Coordination abilities of mono and multi-histidinic and glutamate peptide fragments towards manganese(II) and cobalt(II). In: ISMEC 2012: 23. International symposium on metal complexes, 18-22 June 2012, Lisbon, Portugal. [S.l.], ISMEC Group / Universidade Técnica de Lisboa. p. 200-201. (ISMEC Group Series, 2). ISSN 2239-2459. Conference or Workshop Item.

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It is known that rich repeat domains in peptides can be of interest as the models for the study of molecular phenomena related to metal ion binding in proteins involved in neurodegenerative disorders. Imbalances in transition metal ions are assumed to contribute to the conversion of the multi-histidinic amyloid β-peptide (Aβ) from its soluble form to an amyloidogenic form, and to Aβ deposition. Of these ions, it has been reported that manganese binding to PrP is detrimental and causes a conformational change in the protein, suggesting that manganese binding could potentially play a role in prion disease progression in vivo. It appears that PrP is less stable on binding manganese and quickly converts to a misfolded form. The binding of manganese to PrP potentially results in the conversion of the protein to an abnormal isoform with properties reminiscent of PrPsc. In particular, although PrP can bind the same number of manganese atoms as of copper atoms, the resulting protein becomes proteinase resistant, forms fibrils and loses function.[1,2]
Regarding cobalt, a novel low-affinity binding site for Co(II) was discovered between PrP residues 104 and 114, with residue His111 being the key amino acid for coordinating Co(II).[3] Thus, despite the interest in manganese and cobalt binding to PrP, a thorough analysis of the interaction of both metals with proteins related to brain pathies has not yet been reported. The (T1R2S3R4S5H6T7S8E9G10)3 fragment from Cap43 protein, which is induced by metal ions, is characterized by a decarepeat domain comprising three decapeptide units with one histidine and one glutamate residue in each repeat. Therefore the study of the interaction of the 30-aminoacid peptide from Cap43 protein with metal ions can contribute to the understanding of the crucial role of multi-imidazol and glutamate sites in the protein coordination processes and the possible role of divalent metal ions in the pathogenesis of prion disease and other related protein pathies.[4-8]
Here we present our recent results on the Cobalt(II) and Manganese(II) complexes of terminally protected mono- and multi-histidine-glutamate peptides studied by combination of potentiometric measurements and spectroscopic techniques (NMR, UV-Vis and EPR). Metal complexation induces important structural changes with the C-terminal portion of the ligand, constraining it to leave its disordered conformation and promoting side chain orientation. Our results give rise to a molecular model of the induced structure for the peptides complexed with cobalt and manganese.

Item Type:Conference or Workshop Item (Poster)
ID Code:8921
Uncontrolled Keywords:Multi-histidinic peptide, complexes, manganese(II), cobalt(II)
Subjects:Area 03 - Scienze chimiche > CHIM/09 Farmaceutico tecnologico applicativo
Area 03 - Scienze chimiche > CHIM/03 Chimica generale e inorganica
Area 03 - Scienze chimiche > CHIM/01 Chimica analitica
Divisions:002 Altri enti e centri di ricerca del Nord Sardegna > Porto Conte Ricerche, Alghero
001 Università di Sassari > 01-a Nuovi Dipartimenti dal 2012 > Chimica e Farmacia
Publisher:ISMEC Group / Universidade Técnica de Lisboa
Publisher Policy:Authors retain the copyrights of their acta, and their unrestricted use, distribution and reproduction in any medium are permitted, provided that the original work is properly cited
Deposited On:03 May 2013 10:58

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