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An NMR study on nickel binding sites in Cap43 protein fragments

Zoroddu, Maria Antonietta and Peana, Massimiliano Francesco and Medici, Serenella and Anedda, Roberto (2009) An NMR study on nickel binding sites in Cap43 protein fragments. Dalton Transactions, Vol. 2009 (28), p. 5523-5534. eISSN 1477-9234. Article.

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DOI: 10.1039/b903305j


NMR spectroscopy was used to study the interaction of Ni(II) ions with C-terminal sequence of Cap43 protein where, from Thr341 to Gly 360 residue, a T1 R2 S3 R 4 S5 H6 T7 S8 E 9 G 10 ten-amino acid fragment is consecutively repeated three times. The behaviour of ends-blocked Ac-RSRSHTSEG-Am (pept1), Ac-TRSRSHTSEG-Am (pept2), and the three repeats Ac-TRSRSHTSEG-TRSRSHTSEG- TRSRSHTSEG-Am (pept3) peptides towards Ni(II) ions was examined at different pH values and, for pept3, at different ligand-to-metal molar ratios 1H- 1H TOCSY, 1H- 13C HSQC, 1H- 1H NOESY and 1H- 1H ROESY multidimensional NMR techniques were performed to understand the details of metal binding sites and the conformational behaviour of the peptides. The results confirmed that each mono-histidinic sequence of pept3 is able to independently coordinate one, two or three Ni(II) ions for 1:1, 1:2 and 1:3 ligand-to-metal molar ratios, respectively. At higher pH values, the coordination of Ni(II) involves imidazole Nδ of His6 and three preceding deprotonated peptide nitrogens from the backbone, giving a {Nδ, 3N-} chromophore in a square planar geometry. In addition, at lower pH values, the involvement of γ-O of carboxyl group from Glu9 residue with the formation of a macrochelate giving a {Nδ, γ-O -, 4OH2O} chromophore in an octahedral geometry, was evidenced. NMR results allowed us to build a model for the structure of the major complex. Structural changes in the conformation of the peptide with organized Arg4 and Thr7 side chain orientation promoted by nickel coordination, were detected.

Item Type:Article
ID Code:3518
Uncontrolled Keywords:NMR spectroscopy, Cap43 protein, nickel binding
Subjects:Area 03 - Scienze chimiche > CHIM/03 Chimica generale e inorganica
Divisions:001 Università di Sassari > 01 Dipartimenti > Chimica
Publisher:Royal Society of Chemistry
Deposited On:25 Jan 2010 09:40

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