Please use this identifier to cite or link to this item: http://hdl.handle.net/20.500.12779/4682
Title: Cu(II) ion coordination to the pentadecapeptide model of SPARC copper-binding site
Authors: Conato, C
Kamysz, W
Kozlowski, H
Luczkowski, M
Mackiewicz, Z
Mlynarz, P
Remelli, M
Valensin, Daniela 
Valensin, Gianni 
Keywords: MATRICELLULAR PROTEIN; TERMINAL AMINO; CELL-MATRIX; COMPLEXES; PEPTIDES; EXCITATION
Issue Date: 2002
Project: None 
Journal: JOURNAL OF THE CHEMICAL SOCIETY. DALTON TRANSACTIONS
Abstract: 
SPARC (Secreted Protein, Acidic and Rich in Cysteine) is a matricellular glycoprotein with many biological functions: it mediates the interactions between cells and the extracellular matrix, playing a role in angiogenesis, tumorigenesis, caractogenesis and wound healing. Proteolysis of SPARC gives rise to a number of oligopeptides which can regulate angiogenesis in vivo and the biological activity of which has been related to their association with endogenous or exogenous copper ion. Human SPARC consists of three distinct modules. Module II is follistatin-like and contains two copper binding sites, the strongest of which-the cationic region 2 (amino acids 114-130)-contains the sequence Gly-His-Lys. In order to shed more light on the biological role of metal complexes formed by SPARC and its fragments, more information is needed on their stoichiometry, stability and structure in solution. In the present paper a potentiometric and spectroscopic investigation on Cu(II) complexes with the SPARC(114-128) fragment, protected at both its amino and carboxylic ends, is reported. This peptide (Ac-TLEGTKKGHKLHLDY-NH2) constitutes a good model to the strong copper-binding site of the protein. The whole experimental data suggest that complex-formation is started by the two His residues, subsequently involving up to three amido nitrogens, as pH increases. The coordination of the two histydyl imidazoles is able to promote amide ionisation in the physiological pH range and this could be the key to the SPARC affinity for Cu(II) ion.
Description: 
27138
URI: http://hdl.handle.net/20.500.12779/4682
ISSN: 1472-7773
DOI: 10.1039/b207029d
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